Ugh... Same, old trope to start a "yuri route" in adult life.
Some people are bi or discover their preferences late, you shouldn't be bitter about that.
I like this, usually the cliché is that it's pretty much always the older woman who introduces the younger one to same-sex relationships.
I'm not a fan of this trope more because it portrays same sex attraction in women as still revolving around men in the form of being hurt by men pushing them towards women. It treats it like some kind of trauma response and leads into all kinds of gross mindsets about "fixing" sapphic women.
I don't hate this trope, but I do think it would be refreshing to see two people meet up like... Normal people, like in a dating site or gay club or just knowing people who are gay or friends who know people who are gay. I feel we don't see enough of that, with the only real long lasting story I can think of doing that being Shiminami Tasogare... Which isn't so much yuri as it is a look into the LGBT community.