Boyfriend might be breaking up with me?

Me and my boyfriend are both 21. We've been together for about a year and a half. As of Sunday everything still seemed fine and normal to me. And he told me he'd see me tomorrow... Well Monday night around 8 I sent him a text asking if he was still coming over and he said he wasn't. When I asked why, he just said he didn't want to. When I probed more he just told me he didn't know what was wrong with him and he just needed his space right now. So for the whole week I haven't really heard from him and don't know what's going on or why. I'll get to finally talk to him in a couple of days. But he has never acted like this the entire time we've been together. We've never had any serious problems or fights. We're a pretty laid back couple. Prior to that night he's still telling me he loves me and talking about next time I come back to his town we'll go to this certain restaurant and everything. I don't think someone can just fall out of love with someone in the matter of a couple days unless he's just been lying this whole time which I don't think is the case. But the only explanation I can think of is he's thinking about breaking up, but I can't think of any reason why... It has been tearing me apart and I can't eat, lost like 7 pounds. I love this guy more than anything and it'll completely destroy me. If anybody has any insight or advice it'd be greatly appreciated.