I'm ready for clover to be someone related to yotsuba with a real beef against uichi.
This is theory, no spoilers at all necessarily... And By related don't mean by blood necessarily, so what if uichi actually became a vet in the main time line but forgot about yotsuha, got married, went on with a regular life, etc. then she crashed out when she found out and that other person is taking revenge for her... Uichi could also had become an asshole for some reason, that would be timeline one.
Timeline two is the first one where yotsuha sees him lose everything and she does nothing to save him, she might even reject him in some way since she says she helped kill him too.
Timelines three to infinity are yotsuha trying to save him and fix whatever caused his disgrace, we are reading about those.