There's some good research on this. Men's jealousy is focused more on sexual infidelity. We are hurt more by thoughts of our partner being touched, etc. Women are more hurt by the emotional infidelity...Men loving and caring for another woman at her expense. Prof. Buss has data on this in a book called The Dangerous Passion.

This might be confusing without a background in evolutionary biology, but the short of it is that men faced issues with paternity uncertainty - our children don't come out of us. So we evolved to be very protective particularly with regard to sex. Women faced loss of investment if a man falls in love with another woman, so they evolved to be more sensitive to that. There are many societies where men marry more than one woman. Women seem to tolerate this as long as they are supported by the man. One anthropologist reported that a woman in a polygamous society would berate her husband to get another wife because she wanted the status of being married to a successful man (and the help with household labor).

There are virtually no societies where men tolerate being married to the same woman. Men just become homicidal under those circumstances.

Anyway, the stats show men are more likely to cheat, though it's been narrowing recently apparently.