Poor Mei… I don’t see how she ends up happy at this point.
She'll find another girl who is also a lesbian and lives happily?
It's an unfortunate thing, but you can't force someone to be gay or bi if they're not, just like you can't force someone to be straight (as much as religious people think you can).
But there are always other people. In the real world, people eventually move on.
As for Tenjin, he's in the wrong with his brother and tutor, as much as it may hurt him. However, his dad seems like one of those old school conservative jackasses who expects his kids to be perfect, which I'm sure didn't help.