Okay, psychologically and worldwide, men tend to want to spread seed and give less emotional importance to the act of sex, while women are more deeply emotionally tied to the act. Women get depressed when having multiple partners because they are not fulfilled. This does not affect men in the same way- but either, having made a commitment, will feel better by the cheating of their partner. Women will count cheating, however, as perception of men giving more attention to something else, not necessarily just someone else. Men don't care as much if women have big hobbies but do have a need for basics being fulfilled.

Generalizations, but the universally stereotypes of centuries have been validated with scientific study; the current behavior of women as they are pushed to imitate men makes both sexes very deeply unhappy. But they are told by therapists to follow superficial indicators and any unhappiness is their fault for (fill in reasons du jour), take another pill.