I have bipolar 1. Give her time. She knows how awesome you are, her mom knows how awesome you are. and I am sure she is trying to be the best version of herself for you. I've been married 11 yrs and I can't count the number of times I told my husband that I wanted to live alone - really to just get my act together. No one has any idea how extremely challenging it is to have Bipolar 1. We don't even understand our own feelings. The most messed up thing is we don't know if we're gonna wake up motivated or depressed. We don't know if we can commit to meetings we agreed to in the evening because our energy and emotions don't really synchronize well. I had times when I had so much motivation to do stuff, but i have zero energy and end up crying and frustrated - you don't want to see this in your partner. FYI - Meds for bipolar is a trial and error type of thing - they prescribe meds, you take it for 2 weeks, wait to see if it works for, only to find it doesn't. Then you go change meds again - only to go through the same cycle again. The side effects of tremors, losing hair, and crying because we think nothing will cure, is something we don't want anyone to see.
I can speak for my self that once I have the right concoction of meds, plus the right therapist, it was heaven for everyone. Fun conversations, energetic, etc. The lows are still there but it's not as bad. My hubby said I bounce back faster than I used to, and don't pick fights anymore. And my husband has ADHD he can tolerate and forget and forgive me faster than typical people without mental health disorders. So give her time and a lot of reassurance. In the meantime maybe there is something you can do like consulting with a psychiatrist on how to help someone with bipolar and reallly understanding the disorder.