I used to wonder, why the divorced fathers never check up on their kids -- they divorced the mother, not the kids. Why they give up. 

I understand it now. Meeting kids is always a painful reminder of the life that could have been, life that was, life that they lost. It's a constant pain. 

It's better to mourn it once and then move on. Not better for the kids, or the father, so not really better, but the pain is one time.