It'd be funny if the guy who has a guro hobby/fetish ended up with a yandere girlfriend.
Honestly, it's not that I think she's yandere in the main chapters yet. More like the building blocks are there, and that her obsession is progressing step by step. There's there's the manga title. I'm not talking about your grandpa's vulgar, generic yandere. More like the slightly disturbed, eccentric, manipulative, and possessive type. Perhaps i'm reading into it too much.