Women, however, were less likely to forgive and forget if their boyfriend had been with another man, the University of Texas at Austin study showed.
Researchers asked 718 college students to imagine being in a long-term relationship and what their reactions would be to several different cheating scenarios.
They found that overall, 50 percent of men would likely continue a relationship with a woman who had a dalliance with another woman, while 22 percent said they could forgive betrayal with another man.
For women, the results were reversed. If their boyfriend cheated with another woman, 28 percent said they'd keep him around, but only 21 percent said they would if he cheated with another man.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Published this month in the journal "Personality and Individual Differences," the study concluded the participant's reactions were based on basic jealousy instincts.
"A robust jealousy mechanism is activated in men and women by different types of cues -- those that threaten paternity in men and those that threaten abandonment in women," said Jaime Confer, the study's lead author and a PhD candidate in evolutionary psychology.
Men, they said, felt more threatened by a rival male because of paternity uncertainty, whereas they saw a female partner's homosexual affair as "an opportunity to mate with more than one woman simultaneously, satisfying men's greater desire for more partners."
Mark Cloud, one of the study co-authors, stressed in an interview that the homosexual infidelity scenario they asked participants to imagine was very rare in reality.
So, the researchers asked participants about their real experiences with cheating. There again, men showed less tolerance of cheating than women.
"Men were significantly more likely than women to have ended their actual relationships following a partner's affair," according to the study.
