By Mark Ryan, BACP Accredited Psychotherapist and NCPS Accredited Relationship Therapist
If you are reading about open relationship rules, something has probably already been said, or very nearly said. Perhaps one of you has raised the idea and the other is still absorbing it. Perhaps you have been open for a while and a recent evening made you realise how little you ever agreed. Perhaps you wrote some rules on a difficult night and are no longer sure they are working. Whichever it is, you are in good company, and most of the pain people describe in this area comes from the same place. It comes from things that were assumed and never said.
This article is for partners at either end of that spectrum, whether you are only thinking about opening up or have been non monogamous for years without ever agreeing the principles. It does not tell you whether to open your relationship. It explains why agreements tend to hold better than rules, how to start with the reasons before the detail, what a good agreement covers, and how to decide in advance how you would pause if you ever needed to. If either of you is afraid of the other, please read the short section on safety first.
Article Summary
Rules usually begin as fears. They protect something precious by controlling what the other person does, and they often fail because the fear underneath is never named.
An agreement is different. It is made by both of you, it is specific enough to know when it is kept, and it can change through a conversation.
Start with the why. Research on consensual non monogamy describes benefits such as need fulfilment, variety and personal growth, and the freedom of your yes matters as much as the decision.
Check whether this is the right time. A recent affair, a relationship in crisis or one partner mostly going along with it are reasons to look at the foundation first.
Words like open, poly and swinging are shortcuts. Four questions tell you more about what you each mean.
Work out what you each need first. A good agreement then covers time, sexual health, information, new people, and home and privacy.
Agree in advance how you would pause, with a calm conversation about why and a plan for how it works, and review the agreement on a schedule.
Why Rules Alone Tend to Fail
Many couples who open their relationship begin with rules. It feels sensible, because rules are quick to write and promise that nothing too frightening will happen. There is nothing wrong with wanting that sense of safety. The difficulty is what rules ask of the people who live with them.
A rule usually begins as a fear. Do not stay overnight. Do not see anyone we know. Do not fall in love. Each one is trying to protect something precious, but it does so by controlling what the other person does, and it rarely says what the fear underneath is. When the fear is not named, the rule is brittle. It gets stretched, tested or quietly broken, and then the conversation becomes about the breach and not about the need.
Many couples also carry unspoken rules, things each partner does or expects that were never said aloud. You often find out they exist only when one is broken.
An agreement is different in three ways. It is made by both of you. It is specific enough that you know when it is being kept. And it is open to change through a conversation. "Do not see anyone we know" is a rule. "We will tell each other before either of us sees someone from our social circle, and talk about it first" is an agreement. The second tells you what to do, and it leaves room for honesty. If you are still at the stage of raising the idea, my article on how to talk to your partner about opening up your relationship may help first, and opening a relationship and what to think about before you do covers the questions to ask yourselves.
Start With the Why
Before you write a single line of an agreement, it helps to know why each of you wants this, or why one of you does and the other is unsure. Reasons are not an exam, and many different reasons are good ones. They do matter, because your reason shapes what you ask for, what you fear and what will feel like success. It is much easier to build something together when each of you can say honestly what you are reaching for.
A review of research on the benefits people report from consensually non monogamous relationships identified three that come up repeatedly, which are need fulfilment, variety of activities, and personal growth and development (Moors et al., 2017). People also come to it through curiosity, or attraction to a particular person. All of those are understandable starting points.
Some reasons need more care. Hoping that opening up will repair something broken between you, trying to stop a partner leaving or having an affair, and going along with something you do not want are all common. None of them is shameful. They are signs that the foundation may need attention first, because an agreement cannot do the job of a repair, and it cannot turn a reluctant yes into a real one.
The freedom of the yes matters. In a study of 56 partnerships in consensually non monogamous relationships in Canada and the United States, people who had sex for more self determined reasons, meaning reasons that felt authentic and freely chosen, reported higher sexual and relationship satisfaction in their primary relationship, partly because their sexual needs were being met (Wood et al., 2021). That study looked at sexual motives and not at whether to open up, so it cannot tell you what to decide. It does fit something many couples learn for themselves, which is that doing something because you want to is different from doing it because you feel you have to.
It is also worth asking whether this is the right time. A recent affair that has not been talked through, a relationship in crisis, one partner being much keener than the other, a major loss, illness or change, or fear of how your partner would react if you said no are all good reasons to pause and look at the foundation first. That is not a failure, and it is not a verdict on whether you could ever be open. A "no" or a "not yet" is a real answer, and it is information about where someone is. It is not an attack. A reluctant yes is not a yes either, and it tends to return later as resentment, so waiting, agreeing a date to come back to the question or asking for help is better than settling.
Which Words Do You Mean?
After opening up, many couples find themselves asking whether they are polyamorous, open, swingers or something else, and discover that they have been using the same word to mean different things. Consensual non monogamy is an umbrella term for relationships in which everyone involved knows about and agrees to romantic or sexual connection with other people. Under it sit many shapes. An open relationship usually means a committed couple who agree that either may have sex, and sometimes date, with other people. Polyamory means having, or being open to, more than one loving relationship at the same time, with everyone's knowledge. Swinging and relationship anarchy are other forms, each with its own meaning.
My articles on open relationships and polyamory and on relationship anarchy go into the differences. The more useful point is that the labels tell you very little about what you have agreed. Four questions tell you more.
Is it sex, emotional connection or both?
Some people are open to sex with others but not to romantic feelings. Others are open to love and have little interest in sex outside the relationship. A partner who pictured only sex can be taken by surprise when the other falls in love, and neither of them has done anything wrong. They simply meant different things.
Is it casual or committed?
A single encounter, an ongoing friendship with sex and a second loving relationship ask for very different amounts of time, honesty and care.
Together or separate?
Some partners meet each other's other partners and share events. Others prefer to keep things apart. Neither is better.
Ranked or equal?
A ranked structure puts one relationship first, which can help that partnership feel secure and can leave other partners feeling that they come second. An equal structure gives each relationship its own weight, and it can make it harder for any one person to feel that their place is safe. Each has real costs, so it helps to decide on purpose.
Research on consensual non monogamy describes benefits such as need fulfilment, variety and personal growth, and the freedom of your yes matters as much as the decision.
Work Out What You Each Need First
It is tempting to sit down together and negotiate straight away. Many couples find it goes better if each of you does some private thinking first, because it is hard to ask for what you want while you are watching your partner's face. The aim is to arrive knowing what is true for you, and not only what you think the other can hear.
Start by separating what you need from what you want and what you would simply prefer. A need is something you must have to feel safe and well in the relationship. A want is something you would very much like. A preference is something you would choose but could live without. If everything is a need, there is no room to build anything. The few things that truly matter, such as honesty, safety, being able to say no and being a priority at times, are worth naming clearly.
It also helps to tell a boundary from a rule. A boundary says what you will do to look after yourself, such as taking a break from a situation in which you are being lied to. A rule says what someone else must do. Boundaries are in your control and they are usually easier for a partner to respect. "I would feel more secure if I knew when you are seeing someone" invites a conversation in a way that "you must tell me everything" does not.
Be honest, too, about the feelings you expect. Jealousy is a normal human feeling in every kind of relationship. It is not a sign that something is wrong, and it is not a reason to stop. It often points to a need such as more time, more reassurance or more say, and naming the need gives you something practical to ask for. My article on jealousy in non monogamous relationships looks at this in more depth.
Finally, write down what helps you feel secure, such as a message when your partner is out, a regular time that is just yours or talking afterwards. Your partner cannot guess these.
What a Good Agreement Covers
Once you have each done that thinking, you can bring it together. A rough shape helps, because a conversation without one tends to drift towards whichever area feels most urgent. Researchers asked 429 people with experience of consensual non monogamy to nominate the practices that help them keep it going, then tested the resulting scale in international surveys of 4,290 people. Nine practices emerged, including disclosing attractions to a partner, open communication about jealousy, sexual health maintenance and thoughtful sharing of resources among partners. Each had its own pattern of association with outcomes such as relationship and sexual satisfaction, so there is no single formula (Mogilski et al., 2026). The areas below line up with those findings.
Time and energy
Time is a common pressure point. Be specific about your protected time together, how you share weekends, birthdays and holidays, how much notice you give, and what happens when plans clash. Look at your real weeks, because an agreement that needs more hours than either of you has will not hold.
Sexual health
This is the part of an agreement that protects everyone, and it is far easier to settle in advance than in the moment. In an online survey of 556 people, those in consensually non monogamous relationships were more likely to report using condoms with their primary and other partners and to have been tested for sexually transmitted infections, and their reported infection diagnoses did not differ from those of people in monogamous relationships. About a quarter of the monogamous participants reported sex outside their relationship, and most said their partner did not know. The survey relied on self report and cannot show why, but it does show that sexual health depends on what people do, and not on the label on the relationship (Lehmiller, 2015).
Agree how you will use condoms and barriers, how often you each test, what you tell each other about testing and practices, and what you will do if a result is positive. NHS sexual health clinics offer free and confidential testing and advice, and they can talk through prevention that suits your situation.
Information and honesty
Couples differ a great deal about how much to share. Some want to know everything, some want only the basics, and some would rather not hear the details at all. Each level has a cost, because knowing everything can feel like too much and knowing little can feel like being shut out. Honesty and privacy are not opposites. The difference lies between not telling and hiding. Agree what you always tell each other, what you tell in advance, what you tell afterwards and what stays private.
New people and other partners
Other partners are real people with their own feelings, and an agreement that ignores them is likely to hurt someone. Think about how you would want to be treated if you were in their place. Some couples agree a veto, where one partner can end the other's involvement with someone. Many therapists and writers on non monogamy are cautious about vetoes, because they can leave other people feeling disposable and put one partner in charge of the other. It is also wise to agree what you will do if you are both drawn to the same person, or if one of you develops strong feelings.
Home, family and privacy
Four studies of how people rate different relationships found that consensually non monogamous relationships are stigmatised, with monogamous relationships rated more favourably on every dimension examined, including by people who were in consensually non monogamous relationships themselves (Conley et al., 2013). That helps explain why many partners are careful about who knows. Agree what is fine at home, how you handle children if you have them, who knows, how you talk about each other online, and what you will do if someone finds out. If being open could affect your job, your children or your safety, agree how you will protect each other.
Agree How You Will Pause Before You Need To
Almost every open relationship will need a pause at some point. A bereavement, an illness, a crisis at work, a new baby or a breach of trust can all make it the right thing to do. Couples who decide how a pause works in advance, while things are steady, tend to avoid having to negotiate it in the middle of distress. It also tells each other that pausing is allowed, and that it is not a failure or a punishment.
There are two parts. The first is a calm conversation about why. When one of you wants to pause, you plan a time to talk, and the person asking explains the reasons while the other listens to understand. It is not a row, and it is not a decision made in a moment of panic. The second part is the plan for how the pause works, which you agree now. It covers how either of you asks for the conversation, how soon it happens, what stops and what carries on, how you tell other partners and who does it, how long it lasts before your first check in, and what has to be true for you to restart. A pause that is agreed this way protects your other relationships too, because everyone gets clarity and not silence.
A pause is not a way of avoiding a conversation, and it is not a tool for controlling your partner. If either of you feels unsafe, afraid or pressured, that is a safety situation and not a pause. When you do restart, go slowly and agree the first small step together.
Keep the Agreement Alive
An agreement written once and never looked at again tends to drift out of date. People change, circumstances change, and what felt right at the start may no longer fit. Put review dates in the diary when you write it, perhaps after one month, three months and six months, then yearly, and after any major change in your lives. A short check in needs only three questions. What is working, what is hard, and what do you want to change. A review is not a test the relationship passes or fails. It keeps the agreement serving the people it was written for.
Agree in advance, too, what you will do when the agreement is broken. Mistakes happen, rules get misread and feelings change. Decide what counts as a mistake and what counts as a breach, how soon you tell each other, how you repair and when you would bring in help. Honesty about a mistake, told early and kindly, is worth more than the mistake. If trust has been damaged, my article on how to rebuild trust after broken promises and lies may help.
If you would like a structured way to work through all of this, I have written a workbook called Our Agreement. It has private pages for each of you, pages for sharing, a template for your own agreement, a pause plan and review pages. It is a fillable PDF that you can type into or print.
If You Are Afraid of Your Partner
A good agreement is freely chosen. It never excuses threats, violence, control or fear. If you are afraid of how your partner would react if you said no, or you feel pressured, controlled or unsafe, that is a separate issue and it comes first. Please do not try to work through an agreement together until you are safe.
The National Domestic Abuse Helpline is free and open 24 hours on 0808 2000 247. They can talk through your options at your own pace. If you are in immediate danger, call 999.
How Therapy Can Help
It can be hard to talk about any of this in your own kitchen, especially if feelings are strong or one of you is much further along than the other. In sessions I help partners slow the conversation down, hear each other and put what they want into words that suit them both. That can mean exploring the why, working through jealousy or fear, repairing a breach, or building an agreement and a pause plan together.
It matters that the therapist you choose is informed and open. In a survey of 249 people in consensually non monogamous relationships who had discussed them in therapy, the most common unhelpful practices were assuming the client was monogamous, lacking knowledge of consensual non monogamy and not being supportive of it. Clients who had looked for an affirming therapist rated their therapists as more helpful (Schechinger et al., 2018). I work with couples of every background and relationship structure, including partners who are thinking about opening up and partners who are already non monogamous, and with individuals who want a space of their own to sort out what they feel.
If you would like to talk it through, you are welcome to book a free 30 minute consultation, in person in London or online. It is a chance to describe what is happening and to see whether working together feels right. There is no obligation, and you do not need to have it worked out.
About the author
Mark Ryan is a BACP Accredited Psychotherapist and NCPS Accredited Relationship Therapist, and the founder of Rise and Grow Therapy, a private practice offering couples and relationship therapy across Kensington, Pimlico, and Angel, Islington in London, as well as online consultations. His approach draws first on Imago Relationship Therapy, alongside integrative relational, attachment based, Gottman, and systemic approaches. Mark works with couples of every background and relationship structure, as well as with individuals working through relational issues.
References
Conley, T. D., Moors, A. C., Matsick, J. L., & Ziegler, A. (2013). The fewer the merrier? Assessing stigma surrounding consensually non monogamous romantic relationships. Analyses of Social Issues and Public Policy, 13(1), 1 to 30. https://doi.org/10.1111/j.1530-2415.2012.01286.x
Lehmiller, J. J. (2015). A comparison of sexual health history and practices among monogamous and consensually nonmonogamous sexual partners. Journal of Sexual Medicine, 12(10), 2022 to 2028. https://pubmed.ncbi.nlm.nih.gov/26395880/
Mogilski, J. K., Miller, G. F., Jonason, P. K., et al. (2026). How do people maintain consensual non monogamy? An international development and validation of the Multiple Relationships Maintenance Scale. Archives of Sexual Behavior, 55(2), 517 to 545. https://doi.org/10.1007/s10508-025-03334-9
Moors, A. C., Matsick, J. L., & Schechinger, H. A. (2017). Unique and shared relationship benefits of consensually non monogamous and monogamous relationships. European Psychologist, 22(1), 55 to 71. https://doi.org/10.1027/1016-9040/a000278
Schechinger, H. A., Sakaluk, J. K., & Moors, A. C. (2018). Harmful and helpful therapy practices with consensually non monogamous clients. Journal of Consulting and Clinical Psychology, 86(11), 879 to 891. https://doi.org/10.1037/ccp0000349
Wood, J., Quinn Nilas, C., Milhausen, R., Desmarais, S., Muise, A., & Sakaluk, J. (2021). A dyadic examination of self determined sexual motives, need fulfillment, and relational outcomes among consensually non monogamous partners. PLOS ONE, 16(2), e0247001. https://pmc.ncbi.nlm.nih.gov/articles/PMC7886188
