It's a rural village in a country that hasn't legalized same sex marriage yet and the majority population seems to be elderly. It does seem like she's worried about the circumstances and not the actual principle. Especially because Kwon genuinely loves this village, puts so much money and effort into maintaining the livelihoods of the people living in it, and doesn't seem to ever want to move.
Her not even talking about this with him and actively trying to break them up is rude and the part I have a problem with but her worries aren't unfounded
I think it's both things, she's just worried about him in her own misguided way. She's definitely wrong in making assumptions and doing things behind his back, but she's also a young college student whose just left the comfort of her rural village. She's definitely going to get a strong wake up call, but I don't think she's some evil bitch like some comments make her sound.
I get that ppl may not agree with that one chick but I believe it's one of those "the road to hell is paved with good intentions" situations. We know she had a complex about her appearance already, so we know that she may struggle with the idea that you don't have to fit a mold to be accepted. And it seems she cares a lot about those around her, so it just seems like she wants to protect ML through a misguided idea of what normal is. ML is already a generally lonely person, so if it's revealed that he's in a homosexual relationship in their little South Korean rural village, he may be isolated even further. My best guess is that the villagers will either not care too much or they'll quickly adapt, especially because they have respect for ML, but the chick doesn't realize that.
Sure it's not her place to dictate who ML can date but it seems she has good intentions and it may not even mean she herself believes homosexuality is wrong. I could be wrong but it seems she's just misguided. It could even mean she herself has struggles with sexuality or maybe it's just that her self-image problems are being projected onto the ML due to stress from her situation. I prefer to wait and see honestly. (づ ̄ ³ ̄)づ