Thank you so much!
I'm really grateful for how many comments & suggestions I've received, they're a big help in my quest to make the game the best it can be.
The next update will include a bunch of home upgrades that tie in with girls' interests, as I wanted these to be more than just conversation topics on dates.
I think your idea about using these to flesh out personalities would work really well. Each personality has certain interests they will always like or dislike (jobs also affect chosen interests, plus randomly selected interests to round it out). So, I could add special dialogue when you engage a certain personality with a home activity tied to their intrinsic likes or dislikes (with an allowance for custom girls who might not fit this).