Jungkook is the popular one, the one you like, and you decide to confess, but he rejects you in a very humiliating way.

You change schools because you didn't want to remember being humiliated in front of everyone.

2 years later, you return to school to make Jungkook regret rejecting and humiliating you, but this time, you were so beautiful that no one recognized you because of how much you've changed.