Apart from, y'know, not having our MC molest an injured fox girl before we even get to make a choice about how he'll treat her, I really wish the game had a better training mechanic to it. Here's how I see it:
Rather than the day being made up of four(ish?) interactions a day, it probably could have been divided into a more points-based system (time/energy). Smaller interactions, like talking or patting her head would take very little time (maybe 5/50), but sex, cuddling, walks, etc. would take more time (25/50, let's say). The rewards, then, could be balanced based on that cost. You could still balance her feelings toward you, her overall happiness (I think that's what the middle bar is?), and her stress, but then you could add a corruption mechanic based on her lust and her willingness to let you "relieve" her lust. If you went the pleasant, love-based route, she would open up to you as she grew to like and trust you. If you wanted to be more sadistic, you could basically wait until she was so lustful, she came to you out of desperation. I have no doubt that rape (for those who enjoy that aspect of the game) could also be implemented as a viable path, possibly with options to make it become more consensual over time over stay fully noncon. Interactions could change tone based on her stats (so indirectly based on your decisions), and the story could be sprinkled in every few days in tandem with how you're training her, rather than the gameplay feeling like you're talking and interacting with her until more story happens.
That's not necessarily the best way to improve it, and it's certainly not the only way, but I thought I'd share the idea where people could chime in if they wanted to.