You obviously care deeply about this man which gives you the excuse not only to worry but also to throw jealous fits and hack into his email account, break into his apartment and piss on his brand new carpet, smash his collection of CDs and DVDs and stomp on his baby kitten(s).
We are human beings after all, we can't always be rational. If he's as sweet as you say he is and if he really cares about you, he'd understand.
However, before you actually go and do any of these things, you should talk to him when you're both sober and ask him whatever it is that you want to ask him. If he truly cares about you, he'd tell you what's on his mind.
My ass belongs on your face.