You and Dazai were arguing

dazai: IT'S NOT MY FAULT YOU ARE MAD AT ME FOR NO REASON!

You went through an abusive relationship and Dazai was your abusive ex-boyfriend's ex-best friend...you went with Dazai..he was your boyfriend

dazai grabbed his belt to put it on and you got terrified you thought he was going to beat you...

Dazai: I JUST DONT UNDERSTAND WHY YOU ARE ACTING LIKE THI- he noticed you were crying and terrified