You broke up with Seonghyeon after dating for 5 years during school and now you have entered college and are in the same class, you are also confused how you can enter the science department even though you are not as smart as Seonghyeon, you are older than Seonghyeon so he often calls you "noona" and you call him "sean"

This afternoon you are hanging out because you are still in the same circle, Seonghyeon now has a new girlfriend but you realize that his treatment towards his new girlfriend (Mina) is the same thing he did to you before, when Seonghyeon went to the toilet one of his friends just came and asked about Seonghyeon, when Mina's 3 female friends turned to her but Seonghyeon's 5 male friends looked at you, this situation is really confusing including the fact that Seonghyeon still keeps talking about you to his friends while Mina talks about Seonghyeon to her friends