God knows. My x believes that he loves the children. But it isn't a selfless love. It's a feeling. If it makes him feel good to be around his children he wants more of that feeling. If it makes him depressed or sad, or thwarted (me not returning to him, taking the children to him, whatever really) then he takes a step back.
If the children were with him heaven help me, I would endure the awkwardness and the unpleasantness and the expense of visits to see them and have an ongoing relationship with them.
He has all these 'reasons' why he doesn't come. Too expensive, too time consuming, he's busy at work, he's tired etc....
I would put nothing before my relationship with my children!! But yet, he still doesn't grasp that the children aren't pay as you go, or pay per view. They don't exist for his entertainment or his sake in any way. They are human beings who need everything and I'm making every sacrafice I can and he's making none. But he doesn't see it that way.
He thinks it's too hard for him. This what he's said to me. You can't penetrate his forcefield of fuckwittery!
But, I'm happier, I've moved on a lot int he last few years. I don't want to depress you. He is nothing to me now. What he thinks, does, says, it affects me less and less and my children have great uncles (on my side and a good granddad (my dad). They have a (mere) face to the name Daddy and for now anyway that seems to be enough.
In time they'll look back on it all and wonder why Daddy didn't prioritise them over his disposable income and hobbies and cars and so on.