His mother abandoned him when he was little, she left him with his abusive father (who if it hadn't been for Hyesung's gender mistake, thought he was alpha, who knows what his father would have done to him being Omega) And curiously she came back apologizing when it was known that he had married someone rich, Hyesung refused to see her and told her that he didn't want her in his life, but well, Dojin knew all that but still practically supports her for free xD