By Mark Ryan, BACP Accredited Psychotherapist and NCPS Accredited Relationship Therapist
Why do people cheat? If you have just found out about an affair, you may be asking it every hour, and no answer feels big enough. If you are the person who had the affair, you may be asking it too, and finding that the reasons you give yourself sound thin when you say them out loud. The question matters because the answer shapes what happens next. It also rarely has one tidy answer. People of every age, background and relationship structure have affairs, and the story behind each one is more complicated than the version that usually gets told.
Article Summary
There is no single reason people cheat. Research points to many different motives, and several can sit side by side in one affair.
In my work, an affair is often less about not loving a partner and more about the person's own story, including parts of themselves they find in the affair and do not bring into everyday life.
Cheating cuts across many kinds of people. An affair does not prove someone is a terrible person, and it does not automatically mean the relationship is over.
Understanding why someone cheated is not the same as excusing it. The pain of the partner who was betrayed is real and deserves to be taken seriously.
Attachment patterns, low commitment, personality and opportunity all feature in the research, and what counts as cheating depends on the agreements each couple has made, whatever their orientation or relationship structure.
Therapy can hold more than one story at once, including the hurt partner's, the partner who had the affair, and the relationship between them.
Asking Why When Everything Hurts
For the partner who was cheated on, why is rarely a calm question. It turns up in the shower, in the middle of the night, halfway through a conversation about something else. Was it something I did? Was I not enough? Was any of it real? Your mind is trying to make sense of a rupture, and it reaches for a cause.
For the partner who had the affair, the question can feel just as urgent and a good deal more shameful. You may not fully know why you did it. You may fear that any explanation will sound like an excuse, so you say very little, and the silence is easily read as not caring.
Understanding why an affair happened is not the same as excusing it. It does not shrink the pain of the person who was betrayed, and it does not ask them to feel anything they are not ready to feel. What it can do is give both of you a way of thinking about what happened that is wider than good partner and bad partner. There is room for compassion for someone who has hurt another person, without approving of what they did.
Why One Story Is Never Enough
Two stories about affairs are told very often. The first is that an affair means the relationship is finished. The second is that someone who cheats is a terrible person, and that is all there is to know about them. Neither fits the people I meet, and neither fits the research.
A study of 506 men and 412 women who said they were in monogamous heterosexual relationships asked whether they had cheated during their current relationship, meaning sexual interaction with someone else that could jeopardise or hurt the relationship. Almost a quarter of the men (23.2%) and 19.2% of the women said they had. These were self reported figures from a particular group, so they are not a measure of the whole population. They do show that cheating is not rare, and that it is not confined to a small group of unusual people. In this study, sexual personality traits predicted infidelity in both men and women, and for women low relationship happiness and low sexual compatibility predicted it too. Demographic factors such as marital status and religiosity mattered less (Mark et al., 2011).org/10.1016/j.copsyc.2016.03.008]]).
When so many different people cheat, a single story about what kind of person does it stops being useful. The partner who has been betrayed is not foolish for having trusted. The partner who had the affair is not only the worst thing they have done. Both of those can be true together, along with a great deal else.
Plenty of couples find their way through an affair, and plenty decide to part. Neither is a failure. If you are in the early days, after betrayal, how couples can heal from infidelity and rebuild trust looks at what recovery tends to involve.
What Research Says About the Reasons
It is tempting to assume that people cheat because something is wrong at home. Sometimes that is part of it, though research suggests it is not the whole picture.
A questionnaire study of 495 people, most of them young adults, asked them to describe their own infidelities and why they happened. Alongside the motives that earlier research had found, which were dissatisfaction, neglect, anger and sexual desire, the researchers found others. These included lack of love, low commitment, wanting to feel better about oneself, wanting more sexual variety, and situational factors such as being drunk and not thinking clearly. Insecure attachment went with motives of anger, lack of love, neglect, low commitment and self esteem, while a more unrestricted attitude to casual sex went with wanting sexual variety. The authors describe their findings as moving beyond relationship deficit models of infidelity (Selterman et al., 2019).
That last point is a kind one, in a way. It means an affair is not simply proof that the other partner failed, and it is not simply proof that the person who cheated is shallow. The motives are many, they overlap, and they come from the person as well as the relationship. This was a study of mostly young adults reporting in hindsight, so the details are best held lightly.
Cheating cuts across many kinds of people. An affair does not prove someone is a terrible person, and it does not automatically mean the relationship is over.
When the Affair Is About the Person as Well as the Relationship
In the therapy room, I see something quite consistent. An affair is usually less about the person not loving the partner they have, and more about their own story. Often they have found parts of themselves inside the affair that they do not bring into their everyday life. It might be a lighter, bolder or more playful version of themselves, or a version that feels seen, wanted or less responsible. Or there is something about the affair relationship that they want and have not found at home, and they may not have known they wanted it until it appeared.
That is rarely a comfortable thing to hear, for either person. The hurt partner may hear it as it was never about me, which can feel like a second loss. The partner who had the affair may feel exposed by it. It matters because it changes the question. Instead of what was wrong with us, it becomes what was missing, what was never said and what was the person looking for. Those are questions two people can work on, and they often turn out to be about more than the relationship.
A preregistered study of 810 people recruited through Ashley Madison, a website that facilitates affairs, found that low satisfaction, love and commitment in the main relationship was not a major driver of the affairs, and that the affairs did not predict a decline in those qualities over time (Selterman et al., 2023). The sample was mostly older, straight and male (684 men and 118 women) and self selected, so it cannot speak for everyone. It says nothing about how a betrayed partner feels, which is a separate and very real matter, but it fits the idea that an affair can be about the person as much as the relationship.
In very rare cases, an affair is an exit strategy. The person wants out of the relationship and cannot say so, and the affair becomes the way out. I see this far less often than people fear, and it does not fit most of the situations people bring.
Attachment and Opportunity
Some of the research looks at attachment, which is the pattern we learn early for how close to get and how much to depend on other people. A meta analysis of 17 studies and 13,666 participants found that higher anxiety and higher avoidance in attachment were both associated with more infidelity (r = 0.18), and that dismissive and fearful attachment styles were linked to it too. Preoccupied attachment showed no association (Ghiasi et al., 2024).
This does not mean that insecurely attached people are bound to cheat. The studies were correlational and mostly came from the United States, so they describe tendencies across groups and cannot show cause. It does help explain why some affairs seem to come from nowhere, when a person has been keeping an emotional distance for a long time.
Opportunity plays a part as well. The line between friendship and affair can blur gradually. Emotional affairs and why they hurt explores what happens when the closeness grows without anything physical taking place.
What Counts as Cheating Depends on the Agreement
Couples define faithfulness in their own ways, and orientation does not decide the structure. Many couples of every kind are monogamous, and some agree to other arrangements. A qualitative study that interviewed 39 gay male couples shows how varied agreements can be, finding a wide range from fully closed to carefully structured arrangements that allowed outside sex under certain conditions. Couples handled breaks in their agreements in different ways, depending on what was broken, whether it was disclosed and how the partner reacted. The authors also found that agreements gave couples boundaries, supported a non heteronormative identity and met the couple's sexual needs (Hoff & Beougher, 2010). The couples volunteered, all lived in the San Francisco Bay Area, and none had ended their relationship after a broken agreement, so the findings show how some couples cope and do not measure how most do.
The point for every couple, whatever their orientation or structure, is that cheating is usually about a broken agreement and the secrecy around it, not simply about having sex or closeness with another person. In consensually non monogamous relationships, that distinction matters a great deal. A partner can feel betrayed by a broken rule, or a lie about it, even when the relationship has plenty of room for other connections. If this is close to your situation, gay open relationships and jealousy in non monogamous relationships may help.
How an Affair Changes a Relationship
Whatever the reasons, the effect on the people involved is real. The partner who was betrayed often loses their sense of what was true, and may start checking messages, replaying the past or struggling to sleep. The partner who had the affair may feel shame, relief that the secret is out, and fear of what comes next, all at once.
Trust will not come back quickly and it will not come back because someone says the right words. It tends to return through consistent honesty over time, and through the hurt partner being allowed to ask questions and to be angry. Two articles cover those early and later stages in more detail. Just found out my partner cheated focuses on the first two weeks, and affairs and betrayals a year later looks at what recovery tends to look like after a longer time.
If You Were Cheated On
You are allowed to want to know why, and you are allowed to be furious while you ask. Understanding is not forgiveness, and you do not owe anyone either on a schedule. You are also allowed to take your time over whether you want to stay. Big decisions made in the first days often look different later, and no one is obliged to remain in a relationship that is hurting them.
It can help to decide what you need to know and what you do not. Some people want every detail and others find the details retraumatising. Ask for what helps you, and say so when it stops helping. Look for support outside the relationship too, from a friend you trust or your own therapist.
If You Had the Affair
Taking responsibility and punishing yourself are different things. Responsibility means telling the truth, answering questions without defensiveness and accepting that the other person's hurt is real, even when it is hard to witness. Self punishment tends to pull attention back to you, which is the opposite of what your partner needs.
You may find that you start to understand your reasons slowly. That is normal, and it can feel dangerous to explain them while your partner is in pain. Try not to use your reasons as a defence or a request for sympathy. Offer them when you are asked, as part of the truth, and let them sit beside your partner's hurt without trying to outweigh it. It also helps to ask what you found in the affair that you do not bring anywhere else.
Making Room for Both Stories
When you are both ready, one of the hardest things is to hold more than one story at a time. One partner is hurt and angry. The other is ashamed and also may be trying to understand themselves. Both are real. Neither cancels the other out, and neither needs to be ranked.
For some couples, that is where recovery begins. For others, it is where they discover that the relationship has already changed, and that parting may be the right outcome. If you are unsure which way you are leaning, should we stay together or break up looks at how couples get clarity when they cannot tell.
When This Is About Safety
If you are afraid of your partner, or an affair has been followed by threats, control or violence, please speak to a specialist service first. In immediate danger, call 999. The National Domestic Abuse Helpline is on 0808 2000 247, free and open 24 hours a day. Men's Advice Line is on 0808 8010327, Monday to Friday, 10am to 5pm. Galop supports LGBTQ+ people on 0800 999 5428, Monday to Friday, 10am to 5pm, and until 8pm on Wednesdays and Thursdays. Joint therapy is not suitable where there is abuse or coercive control.
How Therapy Can Help
An affair leaves most people feeling that they cannot have the conversation alone. It tends to explode or go silent. In therapy, I slow the conversation down so that each of you can be heard without it becoming a fight. For the partner who was betrayed, that means space to ask questions and to be angry, with someone who will not rush you towards forgiveness. For the partner who had the affair, it means space to look at why, without being reduced to a single story.
Together, we look at what the affair has shown about the relationship, what each of you wants now, and whether and how trust can be rebuilt. I will not tell you to stay or to leave. I work with people of every background and relationship structure, and I do not assume that any particular structure is the goal.
If you are wondering whether therapy could help, I offer a free 30 minute consultation, in person in London or online. You can ask anything, and there is no obligation to continue.
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 all kinds, including LGBTQ+ couples and those in non traditional relationship structures such as consensual non monogamy, as well as with individuals working through relational issues.
References
Ghiasi, N., Rasoal, D., Haseli, A., & Feli, R. (2024). The interplay of attachment styles and marital infidelity: A systematic review and meta analysis. Heliyon, 10(1), e23261. https://pmc.ncbi.nlm.nih.gov/articles/PMC10754894/
Hoff, C. C., & Beougher, S. C. (2010). Sexual agreements among gay male couples. Archives of Sexual Behavior, 39(3), 774 to 787. https://pmc.ncbi.nlm.nih.gov/articles/PMC2855749/
Mark, K. P., Janssen, E., & Milhausen, R. R. (2011). Infidelity in heterosexual couples: Demographic, interpersonal, and personality related predictors of extradyadic sex. Archives of Sexual Behavior, 40(5), 971 to 982. https://pubmed.ncbi.nlm.nih.gov/21667234/
Selterman, D., Garcia, J. R., & Tsapelas, I. (2019). Motivations for extradyadic infidelity revisited. Journal of Sex Research, 56(3), 273 to 286. https://pubmed.ncbi.nlm.nih.gov/29244527/
Selterman, D., Joel, S., & Dale, V. (2023). No remorse: Sexual infidelity is not clearly linked with relationship satisfaction or well being in Ashley Madison users. Archives of Sexual Behavior, 52(6), 2561 to 2573. https://pmc.ncbi.nlm.nih.gov/articles/PMC10069361/
