Well when I'm down I definately push people away...isolating myself. When I'm up its usually better. It sounds like he is kind of winging it (not having treatment or counseling). Does he seem generally down (depressed) right now?

Ultimately to have a meaningful and lasting relationship with him, he really will need help in the isolating area at least such that he doesn't isolate himself from you. How to get there maybe an interesting road...he's got to want that...he's got to put the time and effort in with a professional...and you probably need to learn about bipolar and how to make sure you take care of yourself...