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Guys who cheat early in a relationship usually fit one of seven patterns: he never saw it as exclusive, a chance came up, he wanted sex or variety, he needed validation, he was angry or felt ignored, he wasn’t that into you, or he has done it before. Research can explain a motive. It can’t excuse the choice, and it can’t tell you which pattern is his.
Below, you’ll find what a large survey found, the seven reasons, what to do if you find out, and what is in your control. Books and answers to common questions come last.
What does research say about why people cheat?
One survey of 495 adults who had cheated found eight motives: anger, sexual desire, lack of love, neglect, low commitment, situation, esteem, and variety. Researchers from the University of Maryland, Indiana University, and the New York City health department published it in the Journal of Sex Research. Men were more likely than women to name sexual desire, variety, and situation. Women were more likely to name neglect.
Two cautions. People reported their own motives afterward, so some may have been explaining themselves. And, per Healthline’s summary, most were young adults, and only about half were in a relationship when they answered. Treat the list as a map of motives, not a forecast for one man.
The lead author, Dylan Selterman, said people cheat for many reasons, “many of which are not a direct reflection of a relationship’s health.” That matters for you. It means a man’s cheating may say little about how good you were to him.
1. He never saw it as exclusive
Low commitment is one of the eight motives, and it includes couples who never agreed to be exclusive. The Maryland team’s example is a relationship where one partner is less committed than the other, or where both didn’t understand it was meant to be exclusive. Healthline adds that people can hold very different ideas about whether a relationship is casual or exclusive.
Early on, that gap is easy to miss. Say you’ve seen Jake for five weeks and you call him your boyfriend. He still has Hinge on his phone and tells his brother “the girl I’m seeing.” Nobody asked. A gap like this doesn’t make cheating okay. It does explain why a lot of early cheating follows a talk that never happened.
What helps: Ask. “Are we exclusive?” takes ten seconds. If he dodges it, you have your answer.
2. A chance came up
The survey puts situations outside a person’s normal, such as being drunk, on vacation, or under high stress, into one motive. Healthline says an opportunity alone can make cheating more likely, though not everyone who gets the chance takes it. Other factors usually pile up too.
Picture Dan on a three-day work trip in Chicago, three drinks in, with a coworker who has flirted with him for six weeks. In our read, early relationships are more exposed to this. A man who has known you for a month has less shared history to protect than one who has known you for six years.
What helps: Notice how open he is about his plans. If he tells you about the trip and who is going, without you asking, he is showing you something. So is the man who turns vague when you ask.
3. He wanted sex or variety
Men in the Maryland survey were more likely than women to name sexual desire and variety. An older study of 432 college students, 120 of whom had cheated while dating, linked sex-driven cheating to being male, being younger, and being comfortable with casual sex (Barta and Kiene, 2005). Healthline notes that desire can drive cheating even in a satisfying relationship. Some people want more partners no matter how good the current one is.
This is the reason that has the least to do with you. In our read, it is also the hardest to see coming. A guy can be warm and attentive and still treat monogamy as optional.
What helps: Take his words about commitment seriously, and check whether his actions match. Don’t try to be “enough.” You can’t out-perform a motive that isn’t about you.
4. He needed validation
Esteem is another of the eight motives: cheating to raise a sense of self-worth. Healthline notes that many people who cheat for this reason have loving, supportive partners. They may think “they have to say that,” while praise from someone new feels more genuine because the newcomer has no obligation to be kind.
Say Leo’s new coworker praises his work twice a day, and by week four he checks for her messages before yours. In our read, your praise hasn’t had time to build up much weight yet in a new relationship, so it can lose to a stranger’s.
What helps: Your reassurance won’t fix this. It is his work. A man who knows he chases validation and says so is in a different place from one who blames you for not giving enough.
5. He was angry or felt ignored
Anger and neglect are two separate motives in the survey. Anger can mean revenge for a partner’s betrayal, or frustration after an argument. Neglect means not getting enough love, respect, or attention. Healthline lists anger at a partner who isn’t around much as one version.
Early on, it can look like this: you had your first real fight on a Sunday, he went quiet, and by Tuesday he’s messaging an ex. In our read, that is a man who doesn’t yet know how to say “I’m hurt” out loud.
What helps: Watch how he handles the first conflicts. Feeling ignored is a reason to talk or to leave. It isn’t a license to cheat.
6. He isn’t that into you
Lack of love, meaning lost passion or interest, is one of the eight motives. Healthline points out that the rush of falling in love fades, and a person may then find the feeling isn’t there. In a new relationship, that can happen fast. By week six the excitement is gone, and he finds he doesn’t feel much underneath.
Some men cheat instead of ending it. Healthline says some people cheat because they want out of the relationship. That is less about you than about his unwillingness to say a hard thing.
What helps: If you suspect this, ask him straight whether he wants to continue. A clear no hurts, but it is easier to live with than a vague maybe.
7. He has done it before
Past cheating is a risk factor for future cheating. A study that followed 484 adults through two relationships found that people who cheated in the first were three times as likely to cheat in the next. People who knew their first partner cheated were twice as likely to report it again from the next one. The University of Denver authors say the pattern held for both genders and married or not, after accounting for demographic risk factors. It was self-reported, though. Healthline adds that some people cheat repeatedly and others don’t.
In our read, listen to how he talks about his past. If all three of his exes are the villain and he never owns a part, you should take a second look.
What helps: Treat it as a risk factor, not a verdict. Ask about past relationships early, and listen for ownership, not excuses.
What should you do if you find out he cheated early on?
Take care of your health first, then decide at your own pace.
- Get tested if you were sexually active with him. The CDC says STIs often have no symptoms, and a healthcare provider can tell you which tests fit your situation. Confidential, free or low-cost clinics exist if you don’t want to ask your regular provider.
- Give yourself time before you decide. In our read, you don’t owe him an answer on the spot. 24 to 48 hours to think is reasonable.
- Ask what you need to know, and skip the details. Healthline says learning his motive may help you decide, but it may be better to avoid intimate details of the encounter.
- Ask whether he wants to continue. Healthline notes that some people cheat because they want out, so it is worth knowing where he stands.
- Watch what he does next. The Gottman Institute’s Trust Revival Method starts with “Atone”: the partner who cheated takes full responsibility and stops blaming or making excuses. That method is written for couples who decide to stay together. In a relationship of a few weeks, you have less shared history to rebuild from, and in our read, leaving is a fair choice.
- Talk to someone who isn’t him. A friend you trust or a counselor can help you sort out your feelings before you decide.
Should you give him a second chance?
There’s no formula, and no study can predict one man. The Denver study shows a higher risk after a past cheater. It also shows many people don’t repeat it. Healthline says working through infidelity can strengthen a relationship, and also that it takes honesty from both people about what they can commit to.
In our read, three things are worth checking. Did he tell you the whole truth, or only what you found? Does he own it without blaming you, your mood, or “the situation”? And do his actions match his words over weeks, not days? Early in a relationship, the cost of leaving is lower, and either choice is valid.
What can you control, and what can’t you?
You can’t stop a man from cheating, and you didn’t cause it. Selterman’s point that many motives aren’t a direct reflection of a relationship’s health applies here. What you can do is lower the odds of being blindsided.
- Have the exclusivity talk early. Reason 1 shows that some early cheating starts with different assumptions. Say what you mean by “we’re together.”
- Say what counts as cheating for you. Healthline notes that commitment doesn’t mean the same thing to everyone. Texting, dating apps, and private dinners are common gray areas.
- Notice small lies. A man who lies about small things, such as where he was or who he was with, is showing you how he handles honesty. Our guide to relationship red flags lists other early signs.
- Move at your own pace. You can wait to be exclusive until you’ve seen how he acts when he’s upset, tempted, or caught in a small lie.
None of this guarantees anything. It helps you spot a mismatch sooner.
Which books can help?
Pick a book that matches where you are. If you want to understand infidelity and its aftermath, look at Not “Just Friends” by Shirley Glass, a psychotherapist who spent her career on infidelity research, according to NPR’s 2003 remembrance. The paperback runs 448 pages, from Atria Books.
If you find yourself drawn to men who keep you guessing, our review of Attached and adult attachment science explains the styles. For more options, browse our relationship books sorted by problem.
Why do guys cheat early in a relationship: FAQs
Why do guys cheat even if they love you?
Motives are mixed, and many aren’t about how good the relationship is. The Maryland survey found eight different motives. Healthline says many people who cheat love their partners and don’t want to hurt them, yet the damage is still real.
Is it cheating if we weren’t official?
It depends on what you two agreed. Healthline notes that partners can hold very different ideas about whether a relationship is casual or exclusive. If you never had the talk, the hurt is still real, but it is harder to call it a broken promise. Use it to decide what you will accept, and to have the talk next time.
What is the number one reason men cheat?
No single reason holds up. The 495-person survey found eight motives. Men were more likely than women to name sexual desire, variety, and situation. Be wary of any list that crowns one reason for every man.
Can a man who cheated change?
Some do, and many need real work. Healthline says some people cheat repeatedly and others don’t, and it points to individual therapy and better communication as ways to lower the risk. The Denver study found past cheating raised the risk in the next relationship. Look for him owning it and showing different behavior over time.
Did I cause it?
No. Cheating is his choice. He could have talked to you or ended the relationship. The Maryland lead author said many motives aren’t a direct reflection of a relationship’s health. That doesn’t mean there were no problems. It means problems don’t make cheating your fault.
Sources
- Selterman, D., Garcia, J. R., & Tsapelas, I. Motivations for Extradyadic Infidelity Revisited. Journal of Sex Research (online 2017; vol. 56, issue 3, 2019).
- University of Maryland, College of Behavioral and Social Sciences. Why do People Cheat? UMD Research Identifies 8 Motivating Factors (January 2018). Page
- Healthline. Why Do People Cheat? 8 Reasons and Tips for Moving Past It. Article
- 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. Abstract
- Barta, W. D., & Kiene, S. M. (2005). Motivations for infidelity in heterosexual dating couples. Journal of Social and Personal Relationships, 22, 339–360.
- Centers for Disease Control and Prevention. Getting Tested for STIs (updated March 2026). Page
- The Gottman Institute. Reviving Trust After an Affair (part 2). Article
- NPR. Remembering Dr. Shirley Glass (October 2003). Page
- Glass, S. Not “Just Friends”: Rebuilding Trust and Recovering Your Sanity After Infidelity (Atria Books, 2004). Amazon listing, checked October 2026.
This article was drafted with AI writing tools and edited by the Truth In Flirting team. It is general information, not therapy or personal advice. How we use AI.
