The separation wasn't his choice. The court process wasn't fair. The contact arrangement was thin. He could have spent years drowning in the unfairness of it, and for a while he did.
What changed: he stopped trying to be the perfect dad in the time he had, and started being a real, regulated, available dad. His kids felt the difference long before they could name it.
Composite story. Details have been changed to protect identities and do not refer to any single individual.