I'm going to try to come up with some ideas for curses based on what is already here in terms of game mechanics.
The Curse of Swapping Scales: Fat and Muscle values will switch after sleeping every night. This also applies to enemies, making for a unique experience. Some enemies will have higher stamina to compensate for this.
The Curse of Boyfriend: While I know this is in development, the curse itself could be an interesting concept. Your character's goal is to get the boyfriend to get out of his apartment. Due to the boyfriend's hermit nature, or the convince of writing, the boyfriend cannot outgrow the apartment due to him having it enchanted to be bigger on the inside. The boyfriend will have a job, allowing for a daily income after every night. He also has moods and wants. I see a lot of potential for this curse, as for the upgraded version, the boyfriend might lock you in the apartment with him so you don't leave and he doesn't have to leave either. It can lead to a fight, which you either beat some sense into him or talk sense into him. Otherwise he's a sweet and shy guy.
The Curse of Possession: The Ghost possesses you in the beginning of the game but also can visibly decrease your stats outside of battle and sometimes refuses to manifest on certain days. Meaning you cannot just rely on the spirit. You have to find a balance between your power and the spirit's power.
Those are the only curses I can think of right at the moment. So I'll make sure to add more curse ideas later!