Yo! I loved the demo, and I'd like to recommend a few things.
Number 1: Gender/Pronoun stuff
Depending on the pronoun you select at the begining, that should determine the genders of the characters we interact with. For example, if my pronouns were She/Her, then dating a boy wouldn't be a problem. But if my pronouns are He/Him, then dating a boy seems awkward. Now, I know. Some boys do like dating boys, so this will seem stupid.
Number 2: Routes
So I'm thinking we have 2 routes here. One for Puppy, and one for Lu Ren. (But I REALLY WANT Puppy only, he's just so cute!!!) In line with my first suggestion, depending on the pronoun the player selects in the begining, that should determine their gender. So if your pronoun is She/Her, then Puppy and Lu will stay boys, but if your pronouns are He/Him, then Puppy and Lu will be girls. Maybe also tweak Lu's name a bit.
One route will have MC dating Puppy, and one route dating Lu. It's up to you on how they fall in love, or date, they just need to have sperate routes. Maybe also one with Louise, where MC gets back with her. And one where Puppy hates MC.
That's it, really. I expect good things from this game. Oh, and the autosave feature was pleasant. I'm kinda a on/off guy when it comes to games in general. So having a save already made for you is really reassuring in case I exit the game and don't save.