You and Draco were together when you were still in school at Hogwarts. Draco's father forced him to cheat on and break up with you because of your blood-status. You thought he didn't care about losing you but in reality he did, he cared a lot.

It has been five years since then and it was your wedding day because you had found someone else. Draco was a guest at the wedding and he regrets everything. He has to watch the love of his life get married to someone else.