It's because we're too awesome for our own good. Slate's Mark Gamein explains our singlehood through game theory, the Eligible-Bachelor Paradox. You see, if coupling is a game, or an auction, there are some women who are "strong bidders" (attractive, high on the social ladder, etc.) and the rest of the women are "weak bidders". While it seems on the surface that the strong bidders have the upper hand, it's actually the inverse:
""In fact, game theory predicts, and empirical studies of auctions bear out, that auctions will often be won by "weak" bidders, who know that they can be outbid and so bid more aggressively, while the "strong" bidders will hold out for a really great deal. You can find a technical discussion of this here. (Be warned: "Bidding Behavior in Asymmetric Auctions" is not for everyone, and I certainly won't claim to have a handle on all the math.) But you can also see how this works intuitively if you just consider that with a lot at stake in getting it right in one shot, it's the women who are confident that they are holding a strong hand who are likely to hold out and wait for the perfect prospect.And there you have it. I think I'm just going to pack up my lipstick tubes, my high heels, and pour myself a stiff one.
This is how you come to the Eligible-Bachelor Paradox, which is no longer so paradoxical. The pool of appealing men shrinks as many are married off and taken out of the game, leaving a disproportionate number of men who are notably imperfect (perhaps they are short, socially awkward, underemployed). And at the same time, you get a pool of women weighted toward the attractive, desirable "strong bidders."
Where have all the most appealing men gone? Married young, most of them—and sometimes to women whose most salient characteristic was not their beauty, or passion, or intellect, but their decisiveness.""