Why isn't this a harem （￣へ￣）everyone is willing to share except cai...

Love cai but my soul is hates him bc I wanna see

I agree this would make the perfect reverse harem. I definitely would love Cai, Calef, and Lukia (he's my fav.) but wouldn't the demon kingdom be stronger if instead of the sacrificial bride, I know it would be extreme, but a demon queen with her powers being able to protect her and grow her husband(s) powers? There's far too many brothers trying to eliminate one another, I'd rather have more brothers working together. Maybe another force like demon hunters could cause some family bonding.