I got the impression it’s sort of a parody on all those crazy yandere ML types and predatory secondary characters from other mangas. Author took every insane situation from other manga and played it up to an extreme. It strikes me as not taking itself too seriously either. So in a way it’s more of a convoluted comedy making fun of stereotypical BL tropes than a romance BL.
But maybe that’s just me

Lowkey think the author of to Koisuru Psycho no Shirayuki-kun writes the story for some hardcore people. The story itself is good, I love stories like it, but the amount of harassment and danger the MC gets into is a bit concerning.