I don't know if it's just a trend, but perhaps past relationships people have been in too?
My cousin and auntie now both consider themselves, both have also been in abusive relationships. My auntie is with a transexual now and they are engaged, I hate him passionately (nothing to do with being trans though). I don't know if I think they are actually bi though, at least not my auntie. I think because of what he's really like (controlling, manipulative) and my auntie being gullible he's put it in her head that she actually is bi. She's blind as a bat to reality, she can't see what's actually happening.