This story really resonated for me. I didn’t realize I was bisexual (although I prefer pansexual) until I was 50 for all the same reasons that you mentioned. A while back I published a story about a private club for bi-sexual and bi-curious women called Skirt Club. It’s gone from being in a few major cities to a worldwide thing. The members are primarily professional women who are involved with men, but want a safe and inviting place to explore their attraction to other women. When I wrote the story, I had all kinds of women contact me to ask if I were a member and could I get them in. Sadly, I am not a member.
I’m a member of a social network for bi-sexual women in committed relationships with men called Married Bees. A lot of the women there have never been with a woman either, but know that they are bisexual.
Recent studies are showing that under the right circumstances, sexual fluidity, particularly for women, may be much more common than anyone ever guessed.