A common observation, about both the Internet dating world and the world at large, is that there is an apparent surplus of available women, especially in their thirties and beyond, and a shortage of recommendable men. The explanation for this asymmetry, which isn’t exactly news, is that men can and usually do pursue younger women, and that often the men who are single are exactly the ones who prefer them. For women surveying a landscape of banished husbands or perpetual boys, the biological rationale offers little solace. Neither does the Internet.
via Online Dating: Sex, Love, and Loneliness : The New Yorker.