That is a major fail. No amount of morality or "personal ethics" can justify that choice. Damn, the scene with her on the beach and in the blue dress. Game Over!
Amy: I swear to God...I swear to God! That is NOT how you treat your human!
I think he over-looked Debra's flaws for the sake of his family, but after she cheated, he realized it and fell for Flor. I think he'd been falling for her a while (like the beach scene). They were kindred spirits and both lived and breathed for their families. I would hope John would leave Debra, but he probably would've stayed for the kids. That was sort of the point of the whole movie. That you live for the ones you love, etc.
By the pricking of my thumbs, something wicked this way comes.