On the topic of fetish grinding/the fetish system in general, I'd really like to see some kind of system where you could allocate points to each fetish category to either make yourself more or less vulnerable to receiving stacks of it, all (except for your chosen weakness at the start) would be a neutral "0" at the start and work how they do currently, you can then remove points from a category (making yourself more vulnerable to receiving stacks of that category) to invest points into a different category (becoming more resistant to receiving stacks of that category).
So for example you could take points out of [fetish A], becoming +33% more vulnerable to stacks (you have 33% chance to get double the stacks each proc), and put the points into [fetish B], gaining a 33% chance to ignore stack applications of this category.
Effectively, this lets the player make fetishes they like less grindy, and also make it less likely for them to develop weaknesses to things they really just don't like.
You can also tie this in to difficulty options, lower difficulties gives you free points to invest and also makes resisted fetishes be able to decay slowly each day, higher difficulties make it so there is a long cd on reapplying points (so you can't just swap out stats for each dungeon all the time).
Completely unrelated but id really really really love if the Malo sleep interaction eventually gave you the option to just snuggle if you want. Maybe you could also wake up with a comfort buff of some sort.
I myself don't mind the grind, and if you want to speed up a few fetisihes you can go into the sim room and grind a girl. But I can see getting a fetish weakness so exp gain is faster, and a fetish blocker so a fetish develops even slower. A way this could work would be something like holding the holy thighble, so anal vaginal and oral develop slowly, but thighs would skyrocket. Or a book on Monster Breeding, which would make it to where Furry, Scaily, and Robot give less exp, but Monster and impregnating go up.
This might be a pain to program and balance, so definitively up to Finchy.
(PS, Finchy has said that since there is a lot of demand for Romancing/being owned by the girls, it is a real possibility in a future update to do something with the free wife. I myself am looking forward to it, but I understand letting him cook. Maybe it will be in 6-9 updates, only Finchy knows.)