Infidelity Statistics: How Common Is Cheating in Marriage?

You’ve probably read that half of all marriages involve an affair. The best data doesn’t support that. Infidelity is hard to study, and many of the numbers online are weaker than they look. This page sticks to figures I could trace to a source, and it says so when the research is thin. I last updated it in October 2026.

If an affair is part of your own marriage right now, you can read how I work with infidelity or book a free first session.

How common is infidelity in marriage?

The best national source is the General Social Survey (GSS), a long-running survey of American adults. In Wendy Wang’s 2018 analysis for the Institute for Family Studies, 20% of men and 13% of women who had ever been married said they had had sex with someone other than their spouse while married.

These numbers have three limits:

• People under-report. The true rates are probably higher.
• The question asks about sex only. Emotional affairs are not counted.
• They count people, not marriages. They tell you how many people have ever cheated, not how many marriages are affected right now.

Who cheats more, men or women?

Overall, men report more infidelity than women. But the gap depends on age. In the same GSS data:

• Under 30, women report slightly more than men (11% against 10%).
• From the early 30s on, men report more, and the gap grows with age.
• Women peak in their 60s, at 16%, then fall sharply in their 70s and 80s.
• Men peak in their 70s, at 26%, and stay high after 80 (24%). At 80 and older, men report infidelity 18 percentage points more often than women.

Some of this is about generations rather than age. Americans born in the 1940s and 1950s, who came of age during the sexual revolution, report the highest rates. As those generations get older, the pattern by age will keep shifting.

Wang also found that infidelity was more common among people who rarely or never attend religious services, and slightly more common among people who did not grow up with both biological parents (18% against 15%). Education made no difference.

Emotional affairs

Many affairs never involve sex, and the research on them is much weaker. There is no reliable national number for emotional affairs. Studies define the term differently, and the figures that circulate online come from surveys I couldn’t trace to a representative sample, so I have left them out.

In my office, many people say an emotional affair hurt as much as a physical one. Texting and social media make it easier to keep a secret connection going, and easier to call it a friendship.

What causes infidelity?

Reviews of the research, such as Blow and Hartnett (2005), keep finding the same factors. These are associations. They show what tends to go along with affairs, not what makes any one person cheat.

In the relationship

• Low satisfaction and emotional distance. Partners who feel disconnected are more likely to look for connection somewhere else.
• Sexual dissatisfaction. Some studies find this matters more for men than for women.
• Unresolved conflict. Resentment that builds for years creates distance.
• Poor communication. Couples who can’t talk about what they need are at higher risk.

Because these patterns build over time, I focus on how couples talk to each other and on the patterns between partners, not only on the affair itself.

In the person

• Attitudes toward infidelity. People who think cheating is acceptable are more likely to do it.
• A history of cheating. One study followed unmarried adults through two relationships. People who cheated in the first had three times the odds of cheating in the second (Knopp and colleagues, 2017).
• Opportunity. Travel, long hours, and close working relationships make an affair easier to start and to hide.
• Attachment style. Some studies link anxious or avoidant attachment to more infidelity.

In my work, most affairs start with someone who is already in the person’s life: a coworker, a friend, or a former partner. That is my experience, not a research finding.

My view: a steadier sense of self

This part is my clinical view, not a research finding. Therapists use the word differentiation for the ability to stay yourself while staying close to someone: to hold on to your own views and calm yourself down without needing your partner to agree with you. Someone who depends on their partner for validation is in a fragile position. When the marriage gets rough, that same need can pull them toward someone who offers validation easily. Helping people build a steadier sense of self is the center of the Crucible approach I use.

Can marriages survive infidelity?

You will see estimates that half to three quarters of couples stay together after an affair. I have not found a large, representative study behind those numbers. Most come from small or self-selected samples, and studies define “staying together” in different ways. Staying married is also not the same as doing well.

The most careful research I know of is small. It followed couples from a clinical trial of couple therapy:

• During therapy. Of 134 couples, 19 were dealing with an affair. They started therapy more distressed than the others. Those whose affair came out before or during therapy improved faster than the other couples, and by the end of treatment they were doing about as well (Atkins and colleagues, 2005).
• Five years later. 10 of the 19 affair couples (53%) had divorced, compared with 23% of the other couples. The affair couples who stayed married were as satisfied as the couples without an affair (Marín and colleagues, 2014).
• When the affair stayed secret. In 5 of the couples, the affair was never revealed during therapy. They ended therapy highly distressed, and 4 of the 5 had divorced five years later.

Read those numbers two ways. An affair leaves a lasting mark, even on couples who work hard in therapy. And couples who get through it can end up as satisfied as anyone else. With so few couples, treat the percentages as rough.

Why secrets make it worse

Secrets keep the damage going. When the betrayed partner senses that something is still being held back, trust can’t start to come back, which fits what the study found. I help the partner who cheated tell the truth in a planned way, and many therapists who specialize in affairs work the same way. That usually means answering the betrayed partner’s direct questions honestly, without volunteering graphic detail.

What predicts recovery?

No reliable statistic exists for this, so this list comes from my own work. Couples do better when:

• Both partners treat the affair as a problem to work on together.
• The partner who cheated takes full responsibility, without blaming the betrayed partner.
• The partner who cheated is open about phones, accounts, and schedules for as long as it takes.
• Both partners are willing to look at what wasn’t working before the affair.
• They get help from a therapist with experience in affairs.

Recovery is much less likely when:

• The affair is still going on, or contact with the affair partner continues.
• The betrayed partner’s pain is minimized.
• The partner who cheated demands quick forgiveness.
• The betrayed partner’s questions go unanswered.
• The betrayed partner is blamed for the affair.

Protecting your marriage

No marriage is affair-proof, but these habits help:

1. Keep talking about things that matter. Talk about feelings, worries, and plans, not only logistics.
2. Deal with problems early. Resentment grows quietly.
3. Keep a sexual connection. Both of you should be able to say what you want.
4. Learn to have hard conversations. Say what you think and want, even when you expect your partner to disagree.
5. Stay whole yourself. Keep your own friendships and interests, so your partner isn’t your only source of validation.
6. Be open about friendships, work relationships, and online activity. If you would hide a conversation from your partner, treat that as a warning sign.

Where to start

If an affair has touched your marriage, the numbers show two things. The damage is real, and many couples do stay together. I can't tell you which way yours will go. I can tell you that people who get help early, and who tell the truth, give themselves the best chance. Start with couples therapy for infidelity. If you want to work on it together, contact me.

Sources

• Atkins, D. C., Eldridge, K. A., Baucom, D. H., & Christensen, A. (2005). Infidelity and behavioral couple therapy: Optimism in the face of betrayal. Journal of Consulting and Clinical Psychology, 73(1), 144-150. doi.org/10.1037/0022-006X.73.1.144
• Blow, A. J., & Hartnett, K. (2005). Infidelity in committed relationships II: A substantive review. Journal of Marital and Family Therapy, 31(2), 217-233. doi.org/10.1111/j.1752-0606.2005.tb01556.x
• Knopp, K., Scott, S., Ritchie, L., Rhoades, G. K., Markman, H. J., & Stanley, S. M. (2017). Once a cheater, always a cheater? Serial infidelity across subsequent relationships. Archives of Sexual Behavior, 46(8), 2301-2311. doi.org/10.1007/s10508-017-1018-1
• Marín, R. A., Christensen, A., & Atkins, D. C. (2014). Infidelity and behavioral couple therapy: Relationship outcomes over 5 years following therapy. Couple and Family Psychology: Research and Practice, 3(1), 1-12. doi.org/10.1037/cfp0000012
• General Social Survey, NORC at the University of Chicago.
• Wang, W. (2018). Who cheats more? The demographics of infidelity in America. Institute for Family Studies.