Guy confusing me - am I sending the wrong signals?

I'd have done the same thing ... it sounds like he does like you but acts different when his friends are around. What's the worst that could happen if you mentioned that to him (not in an accusing way or anything)? If you go up to him and say hello next time you see him, whether his friends are there or not, why not make a comment following up something you talked about in your last conversation - and then say 'sorry I've not talked much lately, when your friends are here you always seem busy'. At least then you'll be up front, and you'll learn a lot about him by how he reacts.