Assassination Classroom
So it's a fem Karushuu AU.
Karma likes Gakushuu so she confesses in their first year at Kunugigaoka. Gakushuu had been about to reject her, but then actually accepted it.
So they date.
They only date for two years before Karma gets sent to 3-E.
That's when Gakushuu asks for a break (because Karma's 3-E now, and 3-E aren't good, her father's always said so-)
So they break up.
They battle and rival each other. They spit venom and words but they really still like each other.
Then after Karma gets first place and Gakuhou gets mad at her, Gakushuu realizes she made a mistake.
After school, she tracks down Karma and apologizes.
They talk it out, and after a lot of feels they're more settled down.
Of course, break ups and getting back together isn't that easy, so it takes a while for bridges to be rebuilt and for trust to be earned once more.
They eventually get back together, and they're a little more happy and content than before they ever broke up.
Then I think of the valentine episode and asdfghjkl what would that be like?
So when Rio sort of confesses of her crush on Nagisa, Karma just goes, "good for you. Korosensei just can't immediately pair his male students with his female students and vice versa, though. Does he even really know our interests?"
And Nakamura's like what.
So Karma leaves Nakamura sitting there staring at her in shock.
And Karma meets up with Gakushuu and they exchange chocolate and gifts and go out on a date.
So a little while later, when Korosensei is being himself again and wanting to interfere in his student's love lives, Karma's like, "eh, but Korosensei, I'm not even single. I already have someone" and the whole class is like what.
And they bug her about it but Karma says nothing except "I already have a girlfriend. Sorry, but the boys you paired me with weren't my type. Maybe 'cause they were boys" and Korosensei starts wailing that he's sorry he assumed her sexuality and how he's proud of her for feeling confident to come out to him.
Then the class attempts to stalk Karma after school to see who her girlfriend is and Karma bumps into Gakushuu and they bicker but Karushuu secretly know they're there. So they silently agree to give the class a show and they just grab each other and a peck on the lips and they leave.
And the class is stone still in shock because Asano is Karma's girlfriend. Asano.
They're rightfully terrified.
As they should be.
That's where the idea ends, unfortunately.