Hypersexuality is common as sugahorse says. But it is not a foregone conclusion that everyone with BP gets that when hypomanic or manic. I don't. I am a lesbian with bipolar. I have dated another lesbian with bipolar. We had a relationship for 5 years. At the end, I found out that she had cheated on me off and on throughout the relationship. I NEVER ONCE cheated no her. And I had BP1 and she had BP2. BP1 has the high mania and the BP2 has the lower level of hypomania. So while I have had hypersexuality when I was single and did some questionable things, I NEVER cheated on my partner. I have to admit, I am sensitive on that subject due to being the one who was cheated on. I would ask you why you are so into a girl you barely know?? What has made her stick in y our head so much? Only you can decide if you can be with someone who may be unfaithful either honestly or in secret. Whether she is manic or not, can you handle being with someone who is not monogamous?