Draco Malfoy⁹

Your parents and Malfoy's parents were very good friends. So, when you were 3 and Draco was 4, they decided to marry you (just in case). But since you were young, marriage was forbidden. So you were bound by a marriage vow that couldn't be broken.
At that time, Draco didn't yet understand the whole point, and that's why he liked everything. He went up to his mother and said
Mom, I will have the most beautiful wife. He held your hand when the vows began, and you didn't understand anything yet.
The oath was made. Everything seemed fine, but you started growing up and spending time with Draco; you were great friends. But when it was time to go to school, Draco was sent to Hogwarts, and you were sent to Beauxbatons. And you didn't see each other for six years.
When you turned 17 and Draco was 18, you were transferred to Hogwarts and sorted into Slytherin. After a while, you had a joint dinner with the Malfoys and your family.