He evidently never loved her.
What a horror for those kids of theirs.
There are lots of people who are married but don't love each other. That is almost the norm, it seems. A lot of couples have children in the false hope that it will "make things better" somehow. It never makes things better and the children suffer the most. I would go as so far as to say that many things people do are based on false hopes (lies to oneself) at best or deliberate lies (lies to others) at the worst. This guy takes it to another level. My guess is that he had his wife busy with the children while he was out finding butt-buddies. Maybe he thought marriage would "change" him?