since there is only heterosexual and homosexual in this universe.........

LOL right

I mean it is Korea... If you're gay, you're disowned. If you're bi, they might say you're still salvageable to become "straight" again, which is the worst form of bi-erasure. I don't even know if there are trans, NB, etc...in Korea either given the lack of human rights.

I'm trying to understand how your comment fits here

I think they're just pointing out how the label bisexual don't really exist in these stories, you're either straight or gay