Sometimes people in hypomania or mania are fickle. It could pass. Though sometimes the disinhibition hypomania/mania brings gives people the courage to do things they want to do, deep down, but normally wouldn't. Maybe he loves you but is resisting feeling limited. Honestly, I don't know. People with bipolar aren't all the same. We're individuals.
It is up to you what to do. Is he taking medication(s)? Is he currently taking them? If not, I, personally, wouldn't call him back until he does. Some may call that brutal, but those same people may think it less brutal if the issue was heroine. For most people with bipolar disorder, supplements alone are worthless!
If your fiance does take medication, but the episode slipped through anyway, he needs a medication adjustment. If he seeks that, that is a positive sign.
Hypomania or mania can be short (days) or long (many months). The length varies based on many factors. Then when that ends, he could possibly fall into depression, which has its own severe challenges.
The course of bipolar illness could be mild (few episodes in life) or downright hellish rough (extreme number in some cases). This is even with proper treatment. Anyone planning to marry a person with bipolar disorder must accept that possibility (through sickness and through health). Obviously, a medication compliant partner is far better than a non-compliant one. Did his bipolar behavior ruin his first marriage? It obviously affects his relationships with his kids (he doesn't live with them, I assume). You describe odd behavior. Is that going to be OK long-term for you, regardless of whether he is on meds or not?
I am the one with severe bipolar disorder in my house. I am not a disgruntled partner. I am disabled. My husband loves me and stands by me, anyway, but I do take my medications and work hard to prevent new ones. Many men would still find my situation too much to deal with, regardless of how charming I may seem, normally. You have to ask yourself what you can deal with. Good sex alone is not enough for people. You can get good sex a lot of places.
Most people in this forum have bipolar disorder. For feedback from others in your position, you may also want to post in
https://psychcentralforums.com/partn...ivers-support/