Bipolar relationships are the hardest. Definitely get therapy for yourself. That should be a huge priority. It will #1 show her you're making an attempt, and you may learn something about this disease you didn't know. Also, living with us is hard.... we make everyone need therapy. ; )
Give her her space when she needs it. And BE PATIENT. Our emotions are incredibly heightened. What you may think you're saying in one wat may be heard by her in a completely different way.
LISTEN TO HER; let her speak;don't interupt; And by listen, I mean don't just hear the words, actually listen to what she is saying, evaluate the meaning. Reiterated back to her what you hear her saying so there is nothing list in translation so to speak.
Learn about our disease. There is a pretty decent list going on here of some really good reads. You never know what you'll learn. And that too will show her that you really do care, and NOT just saying the words.
I've been in this boat many times with my partner, he just couldn't get it for the longest time. We were together almost 3 yrs and it was perfect in the beginning. But then my symptoms starting increasing in severity and frequency. My life suddenly went to hell.I still am not sure if I was misdiagnosed or if I just transitioned. He's trying still today, by doing what I suggested to you. He said going to therapy himself has been very helpful, as well as reading up on the disease.
God luck to you! Remember, we're always here!