Hey Arvus, I'm more of a Romance player than a Slut route player, so the below suggestions/ideas come from that perspective. :)
1) Have Josef leave on his own volition as an option, perhaps through the hinted "Divorce to protect Anna" idea he mentioned (Maybe have a set time in which the debt must be paid to trigger this event, 2 years or something fairly long-ish) or maybe an ulterior motive to leave. I don't per say hate the guy, but don't want to go the Isabelle route or chase the guy away or want to share Anna with him long term since chasing him away doesn't feel like its completely justified in terms of responses available to the Player, despite him having dealings with shady characters and allegedly having mistreated Anna in their marriage to the point where she fell apart in the kitchen because of it. (Loyal to a fault more often than not.)
2) Have a much more clear explanation for Josef leaving when talking to Adrian, explain to him what Josef has done to Anna and his dealings in the past, Mario, Isabelle events in his office, perhaps even the Hitman event etc, maybe mentioning the Isabelle encounter with her claiming that MC, Anna and Adrian are to blame for dragging down Josef, and she making a pass on MC. I feel like options given don't fully justify the disdain towards Josef when he is told to leave, making Adrian an enemy, he hasn't exactly been treated well either, and I'm not one for sharing Anna or any other character just to have him on my side. (Loyalty strikes again...sigh)
3) Be able to play through to the end without engaging with Celeste, my current playthrough I haven't done her quest, but with the use of strategic skills and focus on fans from almost the beginning, I have ended up having a much larger income pool, more than triple the amount of subs, and +10 times more fans than her even though she steals followers every Wednesday, in turn, I feel like this can be a viable way to de-throne Celeste without getting mixed up with her. (Getting some bad vibes from that one, don't like her one bit. lmao)
4) In my current playthrough I did not take Mario up on his offer, while hard at first, I did manage to get the coin for the time being to pay that shady Frank guy until Tristan (bless your soul fr) rocked up, though I am more concerned about what happened to the Frank since he is gone now, temporary or permanent. I'm not keen on using force to get rid of ol Frank. Perhaps have a way to resolve the Hitman issue without resorting to murder or being a village bicycle if he didn't leave permanently after Tristan came around?
5) Option maybe to disable the futa thing for players like myself who aren't all to keen on that, I realize it is optional, and at first, I thought I HAD to share Phoenix with Anna in order to get the Harem ending, the quest log never updating to show I did in fact complete the requirements in the gym may have helped with that expectation, but it would be slightly less awkward to deal with them in the gym, also perhaps extend the activities in the gym beyond just 5 times exercise each training level?
6) Expansion on the main bedroom when Josef is gone. Cuddling is cool, though that being the only thing to do there, feels like the room is under utilized, same goes for the wardrobe and the office, maybe the office can become something of a headquarters for the Starmaker page when Josef is gone or something.
7) Any plans for mod support? I understand that adding mod support is a giant undertaking, just asking out of curiosity since I have made a personal mod that replaces some of the backgrounds in the apartment with my own backgrounds, though probably not the best way to mod the game, but it sort of worked. :P
8) Have a clear quest log for Ken's questline, in my playthrough I had to look at the guide on what to do for his quest after taking the photo in front of the Entrance with Anna, since there was no quest log in the journal about it, not sure if this is a bug though.
140 hours in, I'm not one for visual novels (my first game has been Starmaker Story), but you've done something really good, keep up the great work!