[kevination]

The reality of the NYC dating scene might be more complicated, as documented by Jonathan Soma (you can just read the findings if you don't like enabling Java):

"The switchover from extra men to extra women starts at 35-39 for most big East Coast cities, but doesn't hit New York until 40-44"

http://www.xoxosoma.com/singles/

[sudont]

One thing I've never gotten is that there are more women than men (USA), but men have much higher rates of being unattached. Is this a case of men having multiple partners, or am I misunderstanding the math?

[klipt]

The main reason there are more women is that women live longer. This also means that most of the "extra" women are over 70.

If you break the population down into age groups (e.g. 0-10, 10-20, etc.) most younger groups have more men than women. Combine this with the fact that younger women tend to pair up with older men, and you get more unattached men in the younger groups (but more unattached women in the older groups).