HI Mezzac and welcome to the BB forums.
Sorry to hear about your relationship problems. This a safe place where we can be open to each other and offer support. I don't personally have bipolar but when someone is manic (or hypo-mania which is a smaller mania) they can feel more sexual than usual and this can give them promiscuous urges. I'm not saying this is an excuse but it can be a sign that he has the condition and that it maybe time to get it reviewed again.
Has he every discussed his sexuality to a counselor/psychologist. Sexuality isn't as black and white as was once thought. There are shades of grey. Some people can identify as straight but still have fantasies about having sexual contact with someone of the same gender. This doesn't mean they will or will not act on them. Labelling ones sexuality is also up to the individual and what they feel most comfortable with as well.
Have you gone to a psychologist with him in the past? Have you considered couples counseling? Maybe he is not sure how to let out his feelings and talking to other men is a way for him to express those feelings. However they would be hurtful to you and your relationship because it causing distrust and dishonesty.
This rough patch does not mean he is a bad person, it just means he may have lost his way a little bit. We all have good days and bad days. I think you need to try be as upfront and honest with him as you can and tell him how all this has made you feel. It may make him upset but maybe he needs to know how you truely feel. It maybe helpful to also see a therapist yourself so they can help you articulate this and help you word this out to him in an appropriate mannor (sometimes emotions can make things come out the wrong way).
I hope this helps. Sorry I couldn't be more helpful. I am really glad you have come onto the forums and opened up. It shows how much you care for him as well as your own emotions. Having a balance is essential. You are a strong person and I know you can get through this with some help and support.
