Higeki no Genkyou to Naru Saikyou Gedou Last Boss Joou wa Tami no Tame ni Tsukushimasu - The Savior's Pride

Princess Pride has made it to age sixteen without succumbing to villainy, turning her potential enemies (or victims) into allies all the while. On the night of her birthday party, she meets the charming, handsome prince of another kingdom–and he's also her fiancé! Pride knows that a future of despair awaits him, so she takes it upon herself to protect the prince and guide him toward a happy ending!