"Let's be Friends"?

Riddle me this, why would a guy, who broke up with you, pop back into your life 3 months later and ask to be friends?

I do know this much, a person would only do that if they were looking for something from you, or to get something out of it.  The question is, what?

Are you bored?
Did you enjoy their company but not enough to be in a romantic relationship with them?
Do you feel bad about how you ended it, and by them saying "yes", you feel better about yourself?
Did you think better about your decision and are trying the "let's be friends" line to get back in?
Why would you even want to be friends with someone of the opposite sex, especially someone you've been sexual with?
Why would you offer to be friends with someone you know liked-liked you?  Why would you put them in that position?  Even if you really would like to be friends with them, if you value them that highly, wouldn't you just walk away knowing that it would be painful for that person knowing you don't feel the same way about them?

I just don't have a clue.  It is a game, and I'm not good at games.

I'm leaning towards - just wanted to feel better. 

But, once you start playing the game, it is best to see it through to the end.  If someone has moved on, it's not nice to pop up just to reset the clock.