I wonder if it is her older age that makes it more plausible perhaps? The thing starts because she feels herself more capable than her husband in this situation, is ready to take the matter in her own hand, thinks she is on par with the boss before meeting him, has clear ideas how to handle the problem - all the result of her career and life experience. She assigns herself agency and she feels she has something to lose - both maybe diffent from a young girl.
Completely agree. This is the thing least plausible for me in the toilet scene. It is important to create an alliance with the boss for the storyline, but its not understandable. Only because of sexual frustration which doesn't fit her personality overall. That shouldn't motivate her here to tell him these details. It seems to result from the direct comparison of the performances of husband and boss. She feels the urge to be honest here, but not towards her husband.
Not trying to be controversial, but I'm not so sure that he is a wimp from the start and necessarily as a character. He tries to stand up to the boss in the beginning. He is not particularly brave or strong but also not particularly weak, he seems normal what you could reasonably expect in this position and role. What makes him really weak then is that is wife takes it out of his hands. He senses she has no trust in his abilities. He gehts told he mustn't fight back because of the risk to get fired. And what breaks him totally and makes him a cuck is getting to know first hand that his wife gets off sexually by fucking the boss. He now knows she is not satisfied. This fact breaks him as a man. It's like accepting he has lost in a battle and that's exactly what the boss suggests to him in the last conversation, to accept that. Contrary to other NTS games he has not this fetish in the beginning, but as a result of this brutal fact.