After the war ended, there was decided to be only one way to clean up Draco’s image. Even though you were friends since childhood, he was a jerk. And your families wanted you to do this so badly. To be his lover…or at least to look like you are. This was a way for you and Draco's family to look good to the press. Since Draco's father went to Azkaban, the Malfoy family's reputation had fallen very low and the only way to raise it was to unite Draco with a girl with a surname like Malfoy. And because of their long-standing family relationship with the Malfoy family, your father and mother made a deal.