[speeder]

Women are hipergamous, they stay only with one person at time, but they switch to what they perceive as better ones. Most divorces are early in the marriage, when the woman is still young enough to have her first kids, or more kids beyond her first or second kid, and thus they can still find another man. Also there is research that found out that divorce rates drop when a woman has male children ( but not female, and noone knows why )