That's bcs he experienced trauma from his childhood. He can't move forward in his life bcs he (unconsciously) keeping those experiences thus Character development is really hard for him. Right now he needs therapy and Dojin should encourage and emphatic to him to voice out his problems. But I see some hints of character development on him tho. Can you see them at least? ~.~ no bcs you are too closeminded. I dont see him as a selfish man anymore since well he is worried to his son and to his family.

fr tho, dojin deserves a break. he's busy because of his band, his child and then his husband that only loves money and dick.