I don’t understand why they don’t just have multiple teachers for the multiple girls. Maybe the angry Elf teacher gets a love interest to soften him up and flesh him out.
You can have a different girl for each subject like the swim teacher and a mermaid, or the math teacher and a vampire. But modern RomComs just can’t do that for some reason. It has to be one MC and it will be a harem, wether the story dictates it or not