I don't know him, or his whole story at all, but from things you say it sounds like he's going through an up phase. Some bipolars get very, very social when they are manic. Hence, he's spending time with "fun" people (I use that term lightly because reading books is really fun to me). He, sadly, will crash sooner or later and its really amazing how much you have gathered so you can help him. That's really awesome. I know that the one piece of advice I would give is just don't be too pushy but don't just turn your back on him. Its a very delicate balancing act, I know, but if you can pull it off, you will be a tremendous help to him. Everyone with bipolar should be so lucky as him to have someone like you caring about them.