Responses
His father was pad off to brush it off and instead of letting MC press charges and get a lawyer he sign papers to receive a large amount of money and the assaulters got in no trouble at all. He was basically told to leave from the ML’s life and he ran away as all of that was the final straw for him.

I don't quite understand how YW's life was ruined. I understand that Seoin's brother beat him so badly and his mother knew and hid everything, but is that why he ran away? I thought he ran away ONLY because of his father's abuse and didn't say goodbye to Seoin because of the kiss he saw. I don't know what else happened that time he was beaten that made him leave without telling Seoin.
Now I know the breakdown Seoin must be going through, but I hope he doesn't abandon YW. Poor guy, he's been through so much that he even makes excuses for his hyung kissing him.