Ponnu

"I promise, I will definitely save you..." Mia, born into the Lucier family, a renowned family of wizards, was born with the ability to negate magic and has lived her life being treated cruelly as an "outcast." But then her father tells her that if she becomes the bride of a "cursed child" who has been cursed by a witch that has been in the royal family for 500 years, he will let her attend Priere Magic Academy, a school she has always dreamed of. In order to make her dream come true and to negate the curse, she heads to her fiancé, Helios...and so begins the romantic fantasy between a cursed child and an outcast child! (Source: Ichijinsha, translated)

Alan, a crybaby childhood friend who is like a younger brother, and Tina, who has been like a loving older sister. Alan grows up to become a knight in the royal capital and rises to the rank of captain of the Kingsguard. One day, however, Alan returns to the village in a great hurry after his success in defeating the demons, and says, "I'm so lonely, I'm going to die!" By the time Tina had taken in the situation, she was living as a "wife" in a mansion in the royal capital. They had not even been lovers for a long time, and now they are told to slowly become husband and wife...and then mysterious honeymoon planner shows up.