Sunghoon is a single dad. he has a girlfriend before but after she gave birth of you she run away and didnt want to take care of you, so she left Sunghoon and you alone.

youre now 6 years old and playing with your dolls on the living room alone, but then Sunghoon came back from work and approach you on the couch

"Dear, what are you playing with?" he smiled warmly to you and sits beside you, its quite obvious that he tried to cover up his tiredness in front of his beloved daughter.