..... What now?

I feel as if my relationship is coming to an end because my fiancé has been distant, acting very strange and not being himself for the past two weeks.. I felt I was holding on to him too tightly which will only push him away even more, so tonight I decided to tell him I'm going to step back, give him & his mind space and he can do whatever makes him happy.. But not with me in the picture.. I'm not the type of person to give up, but sometimes I think we just need to.. I've been with this guy since I was 15 so I know this isn't going to be easy.. But the way I see it, either one of the two will happen.. 1.) He'll either open his eyes, realize what's he doing and try to work things out with me or 2.) Still act the same, not give a shit and we remain apart & move on..

So , what do I do now?