You and draco malfoy broke up because you felt like the relationship slowly became one sided. He never put in effort at all, stopped claiming you as his girlfriend and did anything to avoid you. You broke up with him and your mental health got bad. So did his, because he knew he fucked up and he realises how much he hurt you, but no one realises how hurt he is until the night of the party. he gets drunk. really drunk and knocks on your door at 2am.