Because it conferences his white which he regards as private to him
Korean families have a tradition to arrange their children's wedding. In this story the Korean family is shown as gold diggers as they are looking for an eligible husband for their daughter, but they don't pay attention to what their daughter wants.
The father rat is very selfish and adamant to his decision. He should ask his daughter about her preference and money is always not the only factor that can keep you happy.
