No contact from boyfriend, but no apparent reason why?

There's this guy I was dating, who lives in another state. We've known each other for about 7 years. So....he calls me one day, talks and talks as if nothing is wrong, I had no reason to think anything was wrong, then discontinues contact w/me from that day forward. He does not take my calls or responds, but there was no prelude to this. He didn't say he needed space or wanted to break up or anything. This was over 3 months ago and still nothing. What do you make of this?