It Will Be a Reward for the Magician

Amelia has been training hard to become a befitting crown princess. However, she is informed by her fiancé, the crown prince, that he has met the woman of his dreams. He expresses his desire to make his fated person the crown princess and for Amelia to be his concubine instead. To avoid being taken advantage of, she decides to ask the sorcerer Loire, who has saved her country from a crisis and become the country's hero, to marry her as his reward. When she asks him directly, he says, "Do your best to seduce me," and thus the negotiations are successful! She begins to visit Loire intending to have a loving contractual marriage, but...? A doting love fantasy between a sorcerer and a serious young lady♡ (Source: Ichijinsha, translated)