The screenshot appears to show someone who has at least two jobs-- using a mod?-- in addition to being a uni student. In addition to being a mermaid, and also neglecting their needs. No wonder the game can't keep up! The sim is probably desperately trying to eat, sleep, shower, socialize, and play some games on their own, blowing their schedule in the process.
I haven't seen any issues like this myself, but I haven't tried to overload my sims' schedules like that either.