It was pretty hard to read your wall of text, consider using paragraphs when writing such lengthy posts. I did glance through it though and this part stuck out to me. Goes back to my point I made earlier regarding looking to Nat expecting her to be some selfless beacon of morality living purely for Ethan's carnal pleasures.
Yes, this started off as her indulging her husbands fantasies but it also awoke something within herself that she never knew was there. Expecting this drastic change in lifestyle to not change them is a bit naive, and it would also make for very boring writing if the characters don't have some inner conflict with regards to their own desires and what to do with them.
This is like a sexual revolution for Nat, going from being the "perfect" wife, whatever that means, to fucking hung men left and right. Honestly if Nat was the "perfect" wife you are advocating for, god what a boring character that would be, and unrealistic too under these circumstances. Expecting these experiences she is having to not change her in anyway shape or form is silly and show a lack of character progression, stale. Clearly she never knew herself as well as she thought, at least not when it comes to her sexual desires. And I think you are looking at Nat with rose-colored glasses.
Also you said yourself that you knew the genre that the developer is catering to by judging his previous work, so why would you expect something different? Do you expect pizza when ordering hamburgers? And why are you playing the route that is specifically supposed to cater to that audience, I really don't get it...
And my biggest complaint about this game has always been a lack of Nat's inner thoughts, I know that Ethan is the primary perspective and that's fine. But it's a duet, so I wanna see Nat's inner workings as well. Otherwise her actions and behavior will feel out of touch and almost NPC-like. She feels less human. If we got a clearer understanding of her internal struggles and reasoning, then when she does something that might feel out of line we can at least see where it came from, whether you agree with her actions or not.
But unlike you I don't expect Nat to be a saint so it bothers me a lot less. But for you, as someone who looks to her like the "perfect" wife I can understand the frustration when it comes to her behavior, would a clearer understanding of her thoughts/reasoning make it any better? Or do you really just want her to be the perfect angel for Ethan? Cause that would be very boring, and predictable from a writers standpoint.