<human>: My girlfriend and I have been dating for one and a half years and up till recently, things have taken a serious downfall.. For me.

I used to love her with all my heart. Now I would say I love her, but am not "in love" with her. I care about her still and don't want her to be hurt.
 
Lately I have been less and less sexually attracted to her to the point where I need to fantasize just to get off during sex, and I notice more girls now and find myself trying not to flirt. When we cuddle or sit next to each other it no lingers feels special and exciting, just dull and sparkless. 

Earlier in the relationship I mistakenly promised her that I would love her forever.. I know. Big mistake. Now I know that's not going to happen, especially since we are going to different colleges. I feel like i myself would be happier if I broke up with her but this is the problem, I know she would take it horribly. She loves me so much still and she's been hurt so many times In the past. I just dont know how to bring myself to do it. I am at a total loss and I just don't know where or how to begin. I even fear she may be so devastated that she wouldn't  be motivated to go to college or she may quit her job or even hurt herself.
 
Sorry for the rant I just have no one to talk to about this and I am in need of some help. I'm just trying to do the best thing.

Could you distill the essence of the text into 1-3 sentences?
<bot>: I am losing my emotional and physical attractions to my girlfriend who loves me very much still. I know she would be absolutely devastated by a breakup. I don't know how to handle the situation properly, and I am worried about her.