The game has a ton of potential. The situation that the player is dropped into is of course hot as Hell. The world is full of hot women with awesome bodies, and he's told that most of them will want to fuck him and potentially be knocked up by him. Its awesome. But the way that its implemented from there can be pretty frustrating. I would suggest a few changes that I think could make it a much more enjoyable experience without adding or changing most of the assets that are already there.
1) Have the player start only able to explore his own apartment and the palace area where he meets the leaders of the various factions. Lay out and make crystal clear what he's supposed to do early in the game, and give the scenes involving everything with Sophia including joining with her. That will set up the rest and make it a lot less confusing.
2) As is, Sophia points out that the three girls living with him are basically his harem, and even calls them whores, but then he isn't able to do more than the very basics of interactions with them for a long time. It doesn't make any sense. So I think that he should either live with only Sophia at first, or with a few other girls where it takes zero effort to have sex with them. And then make the other three the first ones he is supposed to add to his harem, and he can then go through pursuing them at school and convince them to live with him.
3) After all of that, then introduce the school and everything involved with that. Have all of the different characters there introduced really well, and then make that area, the apartment, the palaces and the shopping zone the only ones the player can travel to.
4) Then gradually open up the world bit by bit from that point, every time giving the player a little bit more choice in where he can go and what he can do. I would say that instead of having the fuel system, simply limit travel based on using up a time of day, and going somewhere and returning to the apartment uses up a given amount of the day. This would simplify it and make it a lot less frustrating.
5) Many games that have the player need to click on an area of the screen to talk to someone or find something have that area glow or be highlighted when they move the cursor over it. This would be a big help.
6) Please, please, please get rid of the food. Having the player pass out from exhaustion because he walked around school or town for a little bit just makes no sense. It doesn't add challenge, it only makes it less fun. I don't understand the point of it at all. Just limiting travel to and from per time of day would solve this entirely.