When I Found a Little Prince, I Was Captivated

Princess Linoa, third daughter of a small country, entered the palace as a candidate to be the First Prince's consort. Due to her mother's low status, she suffered harassment from her sisters and other consort candidates. One night, Linoa sheltered an injured boy named claus, pretending he was her mother's nephew so they could live together. However, the boy's true identity was the First Prince himself, who had been transformed into a child by a curse during a political struggle...! The key to returning him to his adult form was Linoa's kiss...!?

"Shall I kiss your hand?" "Denied. I want to kiss Linoa on the lips."

Is it because that would break the curse? Or perhaps...