i think i missed something

here's pretty much a summary of ch 63 - 67

blonde girl (hyejoo) had a crush on a sunbae but didnt know already had a girlfriend until she went to a drinking party with dawoon. hyejoo ended up catching his girlfriend cheating on him on her way to class. sunbae finds out his girlfriend was cheating on his own and breaks up with her. now that hes single, dawoon acts as a wingwoman to help get hyejoo and the sunbae together.

because dawoon is seen interacting with the sunbae a lot (asking him out for meals and stuff so that hyejoo can come along and dawoon can leave them alone together), rumors go around dawoon was the one interested in him. scummy sunbae hears about the rumor and decides to use it to his advantage since he's still pissed at dawoon and hyejoo.

because hyejoo feels self-conscious, she starts getting a feeling that dawoon and subae might have something going on too, despite dawoon helping her set them up. dawoon gets a text from the sunbae to come over to his place. it turns out he bought a gift for hyejoo and needed help wrapping it up. the sunbae really does like hyejoo back. a friend of scummy sunbae spots dawoon and subae together outside at night and sends a picture to him and he spreads the photo along with rumors of them dating and sleeping together.

the rumors drove hyejoo and dawoon apart and they never end up talking about it. the sunbae hyejoo liked tried to find out who spread the rumor but couldnt bc it was spread so quickly and he had to leave for practical training

ohhhhh okok i get it now thanks so much for explaining