Aight okokk,
@Lilliwyt was absolutely right with what they said, but I might be a sick bastard and just can't forgive Shizuka for her actions and how she has hurt Mio. I've been in a similar situation, but a relationship isn't a contract for godsake, if things don't work out, you just move on. I'm totally with Kaoru here, she knows what she wants and isn't afraid to admit that to her both are beautiful, but liking someone, even loving someone, is not a goddamn chain. Feelings and relationships are supposed to make you realize how much you enjoy your time together without any obligation whatsoever. (futaribeya inmediately comes to mind with this kind of ideal relationship)
Irl rant aside, I do hope that Shizuka can finally move on from Kaoru with this and this damn "I was supposed to be your only one" arc, because goddamn it's been aggravating for me.