Responses

Even if a student is 18 in the US, it's still generally illegal for them to be in a romantic and especially sexual relationship with their teacher, due to power imbalance. There are loopholes of course, such as parental consent to marriage which is bizarre to think about.
In webtoons and what not, these relationships are written in the best possible light because the author has full control. In real life, these relationships are generally problematic.
As far as I know, in Korea you’re considered an adult once you turn 19. And that’s why the teacher is kinda iffy on seeing fl as anything other than his student.
I’m assuming a lot of us reading are Americans, so it’d be like if an 18 year old starts dating their high school teacher while still being in high school themselves, it’s technically “legal” since the student is of age but it’s still weird. Normally I don’t mind an age gap if they’re both close in age but the issue isn’t just the age, it’s the fact that she’s still in hs. Power imbalance. Like how an 18yro in hs is different from an 18 yro in college, different life experience and what not.