R.,
I am also bipolar. Mine currently is very well controlled and I function very well most of the time, but I have had a few episodes during the past few years. (Luckily I have a magnicifent doctor who helps me to get to feeling better very quickly.) I can tell you that there is no way anyone can truly understand unless they have went through it. My father is severely bipolar and I call him when I am down. Generally it is something along the lines of "But I don't want to be like this, I want to fell better, When does it get easier to deal with?" His answer always has been that it really doesn't get any easier because people can't cope with the fact that you can't just make yourself feel better just because you want to feel better. That is not in our general make-up to accept. People put a big stock in the old saying "Mind over Matter" but with a bipolar person, that isn't possible.
The only real advice I can give you is #1, have him read everything you can find about bipolar disorder online. This way he can read a little about what you are going through and know that you aren't just making it up. #2, don't take things so personally when you are in a depressive state. Sometimes bipolar's, just like everyone else, have a bad day and get down. Being down is a far cry from being depressed for us, but others can't always tell, so we get treated as they would treat anyone else when they were upset. But in some ways, isn't that a good thing every once in a while? Isn't it nice that the guy that you love sees you as just another person and not a disease?
Let me know if you need to talk to someone who lives it.
B.