"Designed To Cheat"

It is all about the chemistry of contraception and it sounds like a plausible hypothesis to me. From what I know of my friends who have divorced it was always the woman who left the relationship.

SciAm: Birth Control Pills Affect Women's Taste in Men

Recent research suggests that the contraceptive pill—which prevents women from ovulating by fooling their body into believing it is pregnant—could affect which types of men women desire. Going on or off the pill during a relationship, therefore, may tempt a woman away from her man.

But for a real eye-opener listen to an interview at CBC's Quirks and Quarks: Sniffing for Sex