I have seen little kids beg their parents to get married. It's beyond unbelievable.
It just shows you what is natural to human beings. Kids instinctively know from the cradle what parents are and that there should be one of each sex and that they should be committed to each other. Alternate situations feel awkward to children. My parents were divorced and I remember plenty of those hollow gut lonely moments. It felt like my home situation was unstable and it was out of my control.