Thanks for writing this. Bi-erasure is real and frustrating.
I'll never forget the time I told my ex-husband I was bisexual. He was going on one of his usual rants about how bisexuals are incapable of monogamy. I had been monogamous with him for 9 years at that point, and I had no interest straying. I just got madder and madder and madder until I told him.
He was shocked and asked me if I needed to be with women. I felt I had found my long-term partner (him) and explained no. I never cheated him, 20 years we were together.
Years later after our divorce, my fellow bisexual girlfriend said to me "People will always assume you are straight and just 'experimenting.' Even if you marry a woman and live with her for 20 years, if that ends and you go on one date with a man, they will assume you're actually straight." I realized she was right. Although I've only been dating women lately, my mother still thinks I'm "in a phase" and somehow waiting for "the right guy" to come along, again apparently.
Also, what's super annoying is the number of straight couples who think my sexuality is there for their sexual three-some hopefuls. Time and time again I've run into a a guy and his girlfriend, the guy dreaming of wanting two women to screw him at the same time, and coaxing his girlfriend that she might really 'be a bit bi' for his viewing and sexual enjoyment. Somehow they're not really down to have a 3-way with a bi-male (that's just two gay. Homosexual sex is apparently for the straight-male gaze, so girls only).
They're not really looking for a relationship, just some kinky fantasy. I had one couple hit me up who were visiting out of town on a dating app who "wanted a cute bi girl for the weekend." I told them to hire an escort, I was not their play thing.
Bi-men are shamed, but bi-women are someone's kink and sexual toy.
Truth is I'm an actual human being with complex emotions and a sexuality and I have deep and meaningful relationships like any other human.