Harry: At the time he didn't tell you, why he broke up with you. You naturally assumed that he moved on, but he didn't want you getting hurt.
Ron: He thought that you deserved better than him and let you go. What he didn't know was that he was the best thing you ever had. You tried making him jealous by getting with someone new.
Draco: He loved you to much, so he had to say goodbye. With Voldemort threatening Draco's, yours and Narcissa life he couldn't take the chance of seeing you gone from his life. So ultimately he told you that he was breaking up with you and walked away. Even though it hurt to hear you crying and not being able to run towards you and pull you into his arms.
Fred: He died, and you will ALWAYS love him, apart of you died with him.
George: He didn't know whether he liked you or Angelina more. But he felt it was unfair if he kept dragging you along with him. Though he realized it was a mistake, it was always you.
Oliver: You had a fight about something stupid and you were both stressed. So he accidentally said, "WE'RE OVER." And it was to late to fit it, you ran out of the common room.
Percy: The same as his family, you believed Harry and tried to reason with Percy. But he took it as a betrayal and broke up with you. You were the one thing that he loved more than his family, and he let you go.
Cedric: You thought that he was getting to close with Cho Chang. Thinking he was cheating you told him off and broke up with him. Leaving his hurt and confused.
Roger: Mainly it was because he thought you were cheating, when he saw you sneaking around with the Weasley Twins. But in reality you were planning a special date with him and the twins were helping. So when he broke up with you, all you did was demolish your special date.
Seamus: He turned his back on your friends and you tried to get him to talk to them. So Seamus being Seamus thought you were betraying him and broke it off. A week later Lavender Brown was on his arm.
Dean: Your parents were Death Eaters and they made you into one. One day you told Dean, he never knew about your parents. So he said you were a no good lier and broke up with you.
Neville: He started hanging out with a girl named Hannah Abbott. Growing jealous you told him that you didn't like him anymore and wanted to break up with him.
Marauders Era
Remus: His fury little problem made him afraid of hurting you. So instead of hurting you he broke up with you.
James: He cheated on you with Lilly Evans.
#nomorewordsneeded
Sirius: When you first said yes to him, he was only chasing you. After 9 months, he started chasing other girls.
#doineedtogoon
Severus: You thinking that he was ALWAYS in love with Lilly and you couldn't blame him. She was everything you were and weren't. That's what you thought, to him it was quite opposite.
Regulus: Like his family, except for Sirius, he joined the Darkside. However you were a muggle-born girl.
Tom- he literally is the cause of so many deaths. Are you gonna stay with a murder, who has a very weird obsession with a teenage boy.