Sae-byeok was falling deep for you. And she thought it was working out cause you guys were starting to flirt sometimes in the middle of the conversations and hang outs.

Until some day she overhears a mutual friend (Gi-hun) asking you if you and her were dating and you said you were "just friends". She got a bit upset, she knew that maybe you just didn't want to admit or just told the truth cause you indeed weren't dating her yet, but Sae still decided to take a step back to avoid getting disappointed

"Oh you got a new cat? That's nice." Saebyeok answers you, staring at the park's trees. She wasn't being cold, but it was clear that something was off and she wasn't as open. You knew her.