Haha... I like this somewhat like a compilation of short stories and how they ended up but the one I like most is the last short story "The Rendezvous" haha... I did not expect that the mother was a bisexual perhaps that is the reason why it was written a former yuri. Sometimes also it runs on blood... it is pass through generation to generation but somehow in the past it perhaps understood and shown in a different way in our present times. hahaha...
Well no, the mother isn't written as bisexual as an actual sexual preference. This is more "Class S" nonsense, where the mother dating girls is seen as something that doesn't count, and has no bearing on her current sexuality. Liking girls and having romances are something that she dropped like baby teeth on graduation, as a symbol of childhood.
I'd love it if she were actually bisexual and just found a dude who fit her tastes, while still finding girls attractive in the same way she sees guys. But the way it's presented, that's not the case.