Not to insult anyone (for real) but although Mi-Ok is misguided, she is not just being nosy for no reason. This story is set in RURAL South Korea, somewhere even farther away from the more progressive views of big urban cities. Too many people are applying their own views on the matter - "Why does it matter?! It isn't hurting anyone! It's none of her business!" But that's not Mi-Ok's or, at a larger scale, SK society's view. They don't see a gay relationship as normal, especially in highly rural areas. Will this story make the villagers raging homophobes? Most likely not, but the fear is real. It is ingrained in some societies that anything apart from the "norm" is to be rejected, which is one of the worst forms of punishments for many. If you're cut off from society, who will have your back? Who can guide you? Who can provide services? Who can you work alongside? Humans are social creatures, isolation from the group can be mentally and physically exhausting. For Mi-Ok, just feeling ousted for being an abandoned child is enough to send her down a spiral - especially as young college student living in a big city without a support system - and while she's wrong about abnormalities in society, she has a point in asking about the validity of their relationship where they live. If she feels ousted due to her smaller situation, how will a gay couple raising a child feel? In a rural community, the help and support provided by everyone is valuable and being ousted of that community is harsh. Aside from possibly being scorned at, harassed, or bullied, they'll be on their own for the rest of time - and while Sung-Ho still has the ability to live elsewhere due to his military background and language skills, will Kwon be able to bear it? Having been taking care of the community basically his entire life, will he be able to stand being isolated? Will he be willing to leave it behind for acceptance and support? Would he even want that? Again, Mi-Ok isn't right, but she's not being "nosy just to be nosy", she seems genuinely worried about someone who is valuable to the community and is like an older brother to her. Not to mention, this isn't the first time this topic has been brought up. At the end of season 1, Sung-Ho's friend from America literally says the quiet part aloud and Sung-Ho sort of agrees.
Friend: "To be honest. I don't think Korea is a good place for two fathers to raise a kid together."
Sung-Ho: "I Know."
Friend: "Are you sure about this?"
Sung-Ho: "No... Not at all."
Sung-Ho is more open to having a relationship with Kwon now, they both are genuine in their love, but is that enough? Can they withstand the possible storm coming? Will they be willing or able to face the challenges? Will they have to raise a daughter in the midst of conflict and rejection? How will their daughter be treated because of her parents? While they might not outwardly say anything to her, the villagers might treat her like an outsider forever, forced to leave when she has enough of being seen as some sort of pariah. Will she resent her fathers for putting her in that situation?
Clearly Mi-Ok is going through a lot and she is barely a young adult, which doesn't excuse that she caused Kwon to be harassed and did take things too far. She feels abandoned, possibly suicidal, and has been dealing with her grandmother's health on her own. I find it weird that people are just seeing it as "a nosy brat choosing to just be a brat" and not as "a mentally unwell young adult with misguided ideas wanting to protect herself and others." Also, I'm not saying you should say "well, she's unwell, she's not wrong!" or "it's okay because she's mentally unwell." What I am saying is that people seem so reactionary that they are genuinely confused as to what Mi-Ok meant because they aren't actually listening to what she is saying but are reacting to her disapproval of a gay relationship. Might it be triggering, sure, but c'mon, please think about her words as well. Personally, I think the village people may be wary at first but will come to accept Kwon and Sung-Ho's relationship, so it will work out, but within the story, it is a real fear that Mi-Ok is experiencing.
Anyways, rant over lol