Plain and simple, ask. But guys hate too direct questions. If he's really important to you, drop everything and go see him. A guy will spend every second with the girl he loves if you haven't seen him in a while. If he asks why you're there and uses excuses like, "I have to go to the store" or worse "I have to work late"...he's probably done with you. Hopefully he'll feel bad enough to tell you he's not into you since you came all the way from wherever. Also, if you guys have said "i love you" and the whole deal, you guys can't be in a long distance relationship much longer unless you guys are Giuliana and Bill.

Oh! p.s. Every visit with him should take your relationship to the next if you guys aren't going anywhere, think about how much you like him.