Because it is, homosexual relationship between the two male characters
The autor herself said it's not
Yaoi is a genre of manga and anime that typically focuses on romantic and/or sexual relationships between male characters, yes I’m aware koogi stated that, but she said it was simply different to traditional yaoi, as it focuses on the psychological aspect and abuse, rather than romance and love. And honestly koogi contradicts herself, she reposts sexual fan art of sangwoo and yoonbum so
Why is this tag as a yaoi??