The end of this lecture has some super interesting reasons for traits we see between male/female in certain species and ultimately in humans. Watch from 1:18:50 onwards: https://youtu.be/Y0Oa4Lp5fLE?t=4730

One very interesting point seems to be that in species where males take on more of a parental role the women are more likely to leave and cheat as their offspring are well looked after versus in species where the male takes on no parental responsibilities they're less likely to leave and cheat as they can't risk abandoning their children.