Men are from Mars, Women are from Hell!

"Research concludes that men are more deeply hurt by separations than women. Men tend to cling longer to dying relationships, and they fantasize longer about their former partners after it is over. On average, men take about twice as long to recover from failed relationships as do women...

...Women express more distress, while men tend to feel more distress but not show it as much...

...It may seem paradoxical that males appear aloof but bond more strongly while females, who seem more openly interested, feel freer to leave. Perhaps the explanation lies in the paradox itself. The sense of being
overly committed already makes men wary of further commitment, while women are freer to pursue intimacy because they worry less about being trapped by it.

The common opinion that women are more emotionally dependent than men shows how nature tricks us. A woman wants a higher level of emotional involvement and is more readily upset when she does not receive it, thereby appearing more dependent. Yet she is more independent, in the important sense that it is easier for her to leave a
relationship and to go on with her life. A typical man is more emotionally dependent in the important sense that he is less able to leave or to withstand the loss if the woman leaves.

The logic of genetic selection accounts for these perplexing traits. The woman who appears dependent obligates her mate to stay and provide for her, thus giving her children an advantage. She makes a man feel responsible for her because she could not make it without him-or so it seems. Yet when it is in her practical interest to leave, her relative independence makes it easier for her to do so than it would be for him.

For men, genetic selection works the other way around. The man who appears strong and stable gives a woman confidence that he can support her, thereby increasing his chances of mating with her and producing offspring. Yet the sense of obligation that bonds him to his wife and children leaves him with less real independence than she has."
This is taken from a book entitled "The Stronger Sex" by Dr. Richard Driscoll, Ph.D. pg 46-47

So just remember, during a breakup, while a woman may cry, whine, sob, pout, and generally act like a two year old, it's probably the guy who is really hurting on the inside.