tough situation

Okay, So I have a problem. It shouldn't be a problem but it is, and there's no rationality behind it. But I think I'm falling out of love. And I don't WANT to fix it either. I went to church camp for a week, and we can't have our phone so I couldn't talk to my bf. And when I came back... I just didn't feel it.... I still love him and care for him deeply, but it's not the same. I hade made plans with him about the future, being married and having kids, that sort of thing. To the point where he actually proposed to me. And it's not like I want to break up with him, but I do. Partly because I don't have that vision anymore. It's hard to imagine us married and such. But I know if I tell him this that it'll break his heart. And I feel horrible because here's no rational reasoning behind it but I can't help how I feel. Funny going is, he holds me in a pedestal, thinks I'm perfect... I hate it..... and I will never find anymore who will love means much as he does. He has given up drugs, cigarettes, alcohol... bf I even helped him renew his faith.... plus, he has extreme anxiety... I don't want to hurt him, but I know I'm going to. What do I do? Any advice?