Humans being fallible and not being able to resist our urges is indeed part of the human condition.

Not my clearest comment. What I mean to say is: "it's the human condition" is being used as a defense/absolution of his affairs, as though it's somehow a matter of course that he's going to commit infidelity. It isn't inevitable, because he could have simply chosen to do otherwise. It may be the human condition to experience temptation, but in the end it's irrelevant. He made a choice. That's what matters.