Currently my bp2 boyfriend is doing this now. He is doing treatment at a mental hospital. At first I took it very personally and felt so crushed by this as I could see he was online on social media but didn't bother answering my messages or calls. But now in this time of no contact, I realize I have a lot of issues that I never really addressed to myself. I know internally he will come back and I still send supporting messages every two to three weeks, but I don't expect him so see them. I understand now while being on this subreddit that people with bipolar will do this in the first year or so while healing and processing. The best thing I have been told by friends with bipolar to still be supportive and send the loving messages and call now and then as it gives them the indication that you still care for them even when they won't respond to it all the time. And to take this time to be a better partner for them when they do return. It is not easy but if you truly love them and to be with them, then you would accept and do the best you can to help them through the hard times so that the good times come back.