Don't want a huge back-and-forth, so just replying to this portion. Of course it's more plausible and natural. A lot more. Couples into that kink/lifestyle are real and in long-term permanent relationships with each other, whether living together or married. With few if any exceptions, those long-term partners still have sex with each other and have some sort of mutual respect and bond, usually just playing out a kink or fantasy together for spice. Without that sort of connection and genuine need for each other beyond a kink, the relationship would fall apart very quickly. The whole cruel-mistress wife/never-inside husband or findom/paypig thing is the stuff of S&M fantasies alone, or some simp paying some camwhore online for private humiliation sessions. A couple could play-act it occasionally, but few if any would/could carry that sort of thing permanently in a real long-term relationship. Everything else is the stuff of exaggerated, poorly written erotica.
You're basically just speaking with authority on something you have no familiarity with, assuming your gut feeling is as good as any.
I hear you and agree with you full-heartedly. When Lena started denying Ian sex I had a Vietnam flashback of Ashley cucking Eric which I couldn't stand, but at least in that game it sort of made sense.
Eric stayed an absolute wimp and valued his self-centered desire to be a hero more than his relationship with Ash. Everybody in his life called that decision stupid, including Arthur and his sister. So cucking him felt like some sort of cruel punishment meant to teach him a lesson. "Oh, so you want to leave me all alone and ignore my needs trying to do some dumb shit, well, have it your way. I know some people who value me more than my own so called boyfriend". And in the pornstar route she logically dumps him because that kind of wimp can't really give her anything anymore.
Ian on the other hand, while may still struggle with self-esteem after his heartbreak with Gillian (even if he has more than enough distractions), is nowhere near being an Eric / Robert / Perry-level wimp (even though occasionally Eva tries to write him this way to give Lena more agency). He's an ambitious young man with a good heart and enough self-confidence thanks to his gym training, his creative pursuits, and even satisfying Lena's submissive needs (making her choke on his cock or fucking her silly). That kind of Ian is not someone who would just take this disrespect and not say anything (even if subconsciously it might turn him on for some mysterious reason). If my girlfriend suddenly decided to talk to me like this, I'd seriously consider that maybe I should dump her before she completely reveals her inner Amber Heard. Or at least have a serious talk with her about what the fuck just happened. It's jarring that Ian never brought this up and never had an agency to nope the hell out of it and dodge the bullet. Sharing kink is hot, being reduced to a sexless voyeur is not.
Don't know if it will change anything, but I shared this concern with Eva, and I hope the cuck / sharing route will at least be a bit more nuanced in the future and won't automatically turn into an abusive relationship where Ian loses his protagonist agency all because he couldn't stop himself from being too curious at the moment of vulnerability which Lena ended up exploiting selfishly.
P.S. Regarding the walkthrough, I've seen several comments asking about it. I'm working on it, but in a relaxed pace to prevent another burnout so don't ask for a release window. After all that's happened it's basically once again become a hobby that barely pays so I prefer to mix it up and do something more satisfying when I'm not in the writing mood. That said, I appreciate that there's demand, but in the meantime kudos to
ffive for taking up the duty of helping the folks here.
P.P.S, still have over 40 pages of discussion to catch up on, so unlikely to respond to fresh messages (can necro old discussions that resonate with me just like this one). Send DMs if you have urgent questions.