would it be : "The Professor's Double Life"?
Pig delta teacher. It's not here tho
it's also called pig delta teacher somewhere and it should be part of this anthology: https://www.mangago.me/read-manga/rut_and_heat_short_story_collection/
but it's not up yet i believe. if you check the chapter uploaded by the scanlation team, the cover of the bl you're looking for is part of it.
does anybody know the english name of ‘el profesor delta’?
i just came across a tiktok video about that yaoi manhwa and i cant find it here