"Even within the gay community, I can’t tell you how many people have told me, ‘Oh, I wouldn’t date a bisexual.’ Or, ‘Bisexuals aren’t real.’ There’s this idea, especially among gay men, that guys who say they’re bisexual are lying, on their way to being gay, or just kind of unserious and unfocused."
Said a man who identifies as a bisexual. He also identifies as a lawyer, and he once represented a lady whose gay neighbors were — as the NYT article "The Scientific Quest to Prove Bisexuality Exists" puts it — "trying to have her dog put down." The man, Brad S. Kane, said he took the side of the dog — not the anti-dog gay guys — because the dog was "the underdog." "The dog needed help, needed a voice."
Nothing I've quoted above says "science" to me. I think there's a social quest to affirm the existence of bisexuality. People choose (or happen) to think of themselves that way and feel that it's mean not to accept them at their word. But that can be a prompt for scientific research. Somehow, I don't believe people really want a scientific answer to the question... unless it's the answer they want.
The lack of scientific orientation is apparent in the article title, which, you'll note, is not The Scientific Inquiry Into Whether Bisexuality Exists.
Suddenly, I feel like paraphrasing Voltaire: If bisexuality did not exist, it would be necessary to invent it.