Do we really need multiple chapters of build up though that we so often get in NTR games? Personally I liked that it all happened quite quickly, it was refreshing.
The wife obviously likes Christian way more than she lets on and is also way more unsatisfied with the husband than she wants to admit. We see her reaction to Christian when they first meet and how much she fancies him.
I'm betting the backyard scene will end up being pure blackmail by the boss. "I'm going to fire your husband tonight, unless you let me fuck you right here."
As for the narrative thrill I think that part of that is how the corruption of the wife is going to play out. She promises the husband at the end that she will always come home to him and probably means it, but I doubt that it will happen. How far will she go from loyal and loving wife to the bosses slut?
Looking at the husband it would be him who would end up in the hospital. His wife fucks his boss, then his boss fucks him up. Double the losses.