Here's an interesting analysis from an article on Alternet:
I was quite irritated with Edwards for that snide remark. Misting up a little does not qualify as "crying". Men do it all the time and they are generally lauded for it.
Clinton's support among women doesn't appear to have come out of Obama's hide -- he won the support of 35 percent of women in Iowa and 34 percent of those in New Hampshire. It does appear that some women who may have been inclined to support Edwards went for Clinton; Edwards had the support of 23 percent of the women caucusing in Iowa, but his support in that demo dropped to 15% in NH -- a pretty significant hit.
Speculation: When Clinton had a tearful moment, Obama responded gracefully, saying that the process is a long grind and all the candidates were exhausted. Edwards, on the other hand, took the opportunity to fire a shot at Hillary, suggesting that America needed a tough Commander-in-Chief. If there was a general sense among women that Edwards and Obama were piling on at the debate and in the days leading up to the vote, it may be that because of Edwards' reaction, he bore the brunt of their anger. Caveat: Edwards overall support was within the pre-election polls' margin of error.
Newsflash to the world: All people are "emotional" all the time. There is no time in anyone's life in which he or she is not feeling some emotion. There is no merit in trying not to feel what we're feeling. If anything, that is dangerous. Suppressing emotions just means they'll come out in an inappropriate way later. And anyone who thinks this doesn't happpen to male presidents can jolly well think again.