Simple, its because you don't have her, or should I say, you
can't get the things you want. Life's ironical, when you have
something, you get tired of it, when you don't have something, you
yearn for it. That's human nature.
So, no need to get jealous dude. Most probably you'll end up
posting "Y i got tired over a previous girlfriend" if the 2 of you
got together. 
