A 2011 study at Tilburg University in the Netherlands, published in the journal Psychological Science, argues that infidelity is also a function of greater economic and social power, which creates confidence and personal leverage for both genders. Women can now use their power in ways to which men have long been accustomed.

A broader cultural shift may also be at work. According to a Match.com study conducted earlier this year by the biological anthropologist Helen Fisher, women are becoming less traditional about relationships. Men, interestingly, may be going the other direction. In the survey, 77% of women in a committed relationship said they needed personal space, as opposed to 58% of men. While 35% of women wanted regular nights out with friends, only 23% of men said the same.

Social networks are another factor, if only by expanding the pool of possible partners. Emotional friendships that turn physical are the traditional point of entry for female affairs. It is now easy for those friendships to take root online. Some argue that social networks are merely an expediter and that cheaters will always find a way. Still, if you’ve never quite gotten over your prom date, today the chances are much better that you can find him.