How to Handle an Apathetic Co-Parent

I often wonder why, when two people get divorced, yet parented together while they were married, they suddenly can't parent together anymore. Is the anger so great that one parent can't see past it or around it? Is the resentment so large that the thought of the best interest of the child is no longer important? Or, was that parent always apathetic towards parenting to begin with?

When I was married, I raised my children virtually alone. I fed them, bathed them, read to them, played with them and taught them. My ex believed that because he worked all day, he was just too tired to parent. Now that we are divorced, he has your standard visitation with a few twists, and he still parents the same way. He is uninvolved and only interested in their religious upbringing. Everything else is a waste of time and energy.

via Lee Block: How to Handle an Apathetic Co-Parent.