Honestly I always thought it was since the mother had left or died the girl of the house has to take her place, in all aspects including the bedroom. Hence the "don't weep", "you, and me and the Devil make three", "She's long gone with her red shoes on gonna need another lovin' baby", and "Come and lay your bones on the alabaster stones And be my ever loving baby" since the father knows it's wrong but does it anyway. Though everyone always says I'm a bit cynical but that's how I see it. No matter what I find it to be a disturbing song yet sung so lovely.