Why do you favor the hypothesis that it's only women who are over-selective?

Trivial understanding of game theory in an evolutionary context, observation of human behavior or accepting the nearly universally acknowledged stereotype (or generalisation) would suggest this hypothesis. Since evolution doesn't 'care' at all about our happiness and given the payoffs for human mating it would be extremely surprising if female instincts were well calibrated for ensuring the individual's wellbeing. The payoffs for males are such that it would be credible to hypothesise from evolutionary reasoning that their selectiveness would any one of too low, just right or too high for the males individual wellbeing.