Congratulations on the project, it looks promising and I'm already looking forward to it!
I've played NTRlegends and a little of NTRholic, and I still intend to finish it.
Here are five suggestions while I haven't finished NTRholic:
1) The idea of different clothes is excellent, but since it's a concern, I would suggest the possibility of customization, perhaps it would be possible to buy the pieces and give them to the girl and dress her according to what you want.
2) Impose deviant behaviors on the girl, such as wearing vulgar clothes, drinking or smoking in front of her husband later in the game, or even getting obscene tattoos.
3) Take the girl to places outside the apartment, such as a square, movie theater or public bathroom and fuck her there.
4)This suggestion goes further away from the base game, is a system of traits/perversions, which would be acquired during the game, such as exhibitionism.
5) At the end of the game, you will have the possibility of turning your husband into a total cuckold slave who watches his wife being fucked and wears a chastity belt. Maybe he will even have his own degradation system.
Regardless of my suggestions, I know they can be complex to implement, congratulations on the project, I can't wait to play it! Good development!