How Many People Cheat in Relationships

Is he cheating? Is she cheating? Tied to emotions of doubt, sadness, suspicion, and anger—at some point this question has crossed the mind of almost anyone who has ever been in love. Although it seems nearly universal to fear a partner will be unfaithful, how many people actually cheat?

In the United States, the odds a man who has ever been married or is living with someone has cheated during the relationship are 1 in 4.76 (21%). For perspective, these are the same as the odds that an adult in the United States never uses swear words in conversation (1 in 4.76). For women, the odds are 1 in 9.09 (11%), the same as the odds that a woman in the United States owns a firearm. Before drawing a solid line between the cheaters and the non-cheaters, it’s interesting to note the gray area. Even a large number of people who aren’t cheating are thinking about it. The odds are 1 in 3.33 that an adult in the United States who has not cheated during a relationship fantasizes about cheating.

While the odds suggest that men are somewhat more likely to cheat than women, a small study published in the Journal of Experimental Social Psychology (PDF) in May 2009 suggests that women might be more likely than men to commit another relationship indiscretion—mate poaching. In fact, single women might be the likeliest to pursue mates who are already in relationships. Researchers based their study on the common complaint of single women: “All the good men are taken.” The study was fairly small but offers some support for the idea that single women are more likely to pursue men who are attached because the men have been “pre-screened” by other women. Similar behavior has also been studied in some animals. While some single people end up accidentally pursuing attached mates, others actively poach; singles can even be found eagerly searching for mates on dating websites geared towards married people.

“Life is short. Have an affair,” declares the front page of, a dating website for married people. Websites like, which launched in 2001, may facilitate cheating in the same way that Internet social networking has facilitated making new friends, but offline locations like the neighborhood and the workplace are still common origins of affairs. The odds an adult in the United States who has cheated during a marriage or live-in relationship did so with a neighbor are 1 in 6.67, and the odds are 1 in 2.7 that he or she cheated with a co-worker. The odds are even higher that he or she cheated with a friend: 1 in 1.45 (nearly 69%). Their motto must be: Life is short. Cheat close to home.

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