The manga I'll always be salty that got cut short is Opapagoto, it was so freaking cute and funny.
The main character is perfect, she's a rough and caring girl.
who gets collared

who ends up at a fancy shoujo school

That for some reason has a pseudo family program (think like the sœur system in marimite) where she ends up being the "father"

Oh and she has a hot "wife" and they kiss

and the characters all have really great chemistry and its so sweet and silly and I wish it had a hundred more chapters