Sad and lost...please help

Ok..well im with this guy and he goes to college…and just awhile ago I was talkin to him online…and we always talk im mean always…but then while he was e-mailing he said he wasnt so happy…and I asked what was wrong and he just said that it was some small dumb thing but that he was going to pay attention to it but then he said that it was just bugging him…then I asked again what was it that was bugging him? And he said that it was someone frm the past…then once again I asked…then he told me that it was someone he use to talk to in his senior yr…so I just bugged out completely and I just told him…”u know I’ll let you go…talk to you whenever bye!” and I logged off the chat room(and I don’t only talk to him in the chat room…we talk in person too) anyways he e-mailed me back asking”what was that for?’ then I completely logged off…my question is what do I do? Does he really love me enough to not let that someone get in the way…the reason I doubt is because he said it was bugging him…what would you do if you were in this problem with your girl friend/boyfriend? Please help!!!