These last several posts are odd to me. Everyone can have their opinion. Yes, there are facts, such as the world being round. When it comes to things such as sexuality, the source information is often....drum roll.....the people claiming they are telling the truth. It is unfortunate that anyone would dismiss something that absolutely no one here can disprove, again, because the source data is based on asking people questions and them telling the truth.
Regardless, does it matter? If one partner is in a committed relationship and the other is bi, Straight, trans, whatever, but does not disclose that information, or in many cases, flat out lies about it, they are not a good partner, period. Would your wonderful bi=husband get a pass for an affair with a man, because its a gay affair vs. cheating with a woman? I mean, thats your life, no judgement..but I would argue that's a horrible partner regardless of the reason.
Science, psychology is a science, but there is a reason is psychology is called a SOFT science. This term is used to distinguish it from "hard sciences" like physics and chemistry, which are seen as having more established, quantifiable, and predictable results. So please spare me the science trumps all, when your science is truly soft at best.
Btw, I agree, I do think bi people exist, but lets not pretend this is equivalent to the round earth, not even close my friend. Enjoy the evening.