Bipolar Boyfriend

When we first got together, we were going out for 4 months. He broke up with me, saying that he didn't love me anymore, but a month later came back to me saying that he'd made a mistake and he'd really missed me, etc. After three months of being together again, he broke up with me for the second time, saying that he just wasn't in love with me. A month later he came back and said how much he loved me, and that he was really sorry.

It was at that point that he told me that he was bipolar. I already knew that an immediate family member of his also has the condition, as he told me this the first time we broke up. Three months later, this month in fact, he broke up with me again, and he says that he doesn't know whether he loves me or not. By now I had seen this coming, but it has still completely broken me.

I'm waiting to see what next month brings, as it always seems to be a month later. A couple of weeks before the current break-up I told him that I was concerned it would happen again but he said not to worry, as he really loves me, and at least his "head" hasn't "gone weird" yet. And every-time, that is how he describes it. He hasn't been diagnosed. However, he says that he experiences all the same symptoms as his immediate family member who has been diagnosed, and his behavior sends up red flags to me.

I can't understand this that well, as I do not experience this myself, but as far as I can understand it, he has recurrent mood swings which changes how he feels about things. He has said before that sometimes he doesn't want to talk to people he used to talk to all the time, that sort of thing. His opinions change on various people / things. I assume this is what is happening when he is breaking up with me. There is a member of my family with bipolar disorder, and he is also the same with the people thing; sometimes he just doesn't want to know his own family, if you get what I mean.

I've given as much information as I can, I just need some advice. I really love this guy; there are no problems with our relationship. When we are together and he is probably feeling "normal" (I hate that word but I'm trying to explain the best I can from my point of view) everything is great. No relationship is perfect, ours included, but it's pretty great...until he doesn't want to be with me.

I'm willing to stick with him, as I really do care for him, and I just need to know what I can do. Is this my fault? Is there any way I can help prevent these mood swings? Should I ask him to see a doctor? Can this be controlled? As in, what can the doctor do? Basically, is there any way anyone can help me, please? I have depression myself, and this is pretty much making me a lot worse.