This game is pretty fun but the balance is out of whack. Played on the default difficulty, not a single sex act until Floor 4, where a defeat loop against those annoying Yetis made my desire buildup so high I can't win any fight without fucking people into submission anymore.
Rather than slow corruption it's more like spikes. I get it's an alpha so balance is likely to be altered eventually.
Oh, and a question: I noticed that I don't have a time limit anymore to conquer Floor 4. I guess it means that floor can't be subjugated?
Yes, beating floor 4 is the current end of content.
The spike you mentioned happens because, while you may have avoided sexual interactions with the prisoners, Karryn's sensitivities and passive desires were likely increasing a LOT from things that were happening during the battles and granting you passives (getting leered, the prisoners jerking off in the open, getting groped, etc). Also if you are winning a lot of battles, Karryn will start developing sadistic desires which will turn her kinky all the same, so all "zero sex" runs are essentially on an invisible timer, or at the very least you need to invest a lot on the "Mind" skill tree to gain desire managing skills for when Karryn inevitably becomes too horny for her own good (speak no evil is what you are looking for). Also the issue is that while desires and sensitivities can raise from passives that don't involve direct sexual interactions, Karryn's sexual endurance mostly only raises from orgasming, which means you might be outclassed by enemies for a while if forced into sex and if your Endurance stat is also low.
You can't escape sexual actions after they are started, and they can't be dodged, but they can only be started if Karryn's desires are past a certain threshold (and most of them will revolve around cock desire, only exceptions I can remember are goblin cunningulus and rogue rimjob if you have that enabled). So with strong "Mind" training you can still avoid sex combat even after Karryn starts being slutty, but if you don't have access to that then yeah, fucking people into submission will be unavoidable.