Wow, she is lucky to have such a devoted friend.
Is it possible she is going through something? Is she really Bipolar, or is that just an idea someone assumed?
If she has been DXed by a mental health professional, and is in treatment, she may be going through some things, non related to you, so it might be good if you don't take her not calling you, to heart.
I get times, I just do not want to answer my calls, kind of like my down time, and I need to be alone or just time for me. I know it sounds odd, but even those I love, I will return a call or tell them I'm relaxing, and I will call them back. Sadly, I'll get caught up in something snd forget to call, or even realize it's too late or early in the day. Giving her space, may be a good idea, but eventually try her again, like the others her have already replied with.
I hope this was of some help, as you get replies to your post, you are going to see the wonderful support the members offer.
Lots of luck with this, and any new job searches you may on.

DE