I don't see where is the problem. I had a friend back in the days, he was 17 and he had a secret crush on a 21yo…
He is an adult, be he should be at school... I really think he is mature, but he is dealing with a lot, I know that happen, I'm 24 and my boyfriend is 27. My problem is not with age difference, but he is still a boy in the high school that still don't pay for his acts. For my context in Brazil he already responds for his acts, but in Korea the majority age is 21. For not having hate on drama (from Korea people) should have a time jump.
IS JUN REALLY 18???
HOPE THERE'S A TIME JUMP!