I'm sorry to hear that this is happening to you!! The thing is, you aren't responsible for how she chooses to treat (or not treat) her bipolar. If she refuses treatment that is her right. However, if she says that she is thinking of suicide, please notify the authorities and let them handle it. I had to do that with someone I loved very much and unfortunately he hated me for it, but in the end I would rather know that he was alive and hated me than have him die by suicide and feel guilty for not taking action.

On the other side, it is your right to tell her that if she does not do her best to maintain her mental health, you will not be able to be with her. I had another friend who was anorexic and refusing treatment and I did have to tell her that I could not be friends with her and watch her die. I told her that as soon as she was willing to work at getting well, I would be right at her side to help however possible. A week later she checked herself into a hospital, and she was still angry with me for several months, but in the end she did call me and thanked me for my "tough love".

So I guess in my opinion, it might be best to let her know that you care about her and want to help her if she is willing to help herself, and tell her to call you when she is ready to try and get well. Because as long as she refuses treatment, things most likely will not be happy in your relationship. That's just my 2 cents of course, and whatever you decide I wish you the best!!