Episode 9 of Crushology 101 begins with Jae-yol walking Bunny home after spending time together. They part ways sweetly, and the next morning, Jae-yol picks her up so they can go to school together.

As the couple strolls hand-in-hand, Jae-yol’s friends are taken aback by the new relationship status. He formally introduces Bunny as his girlfriend, and Dong-ha seems genuinely pleased. Bunny’s friends are equally supportive, while Ji-won forces a smile as Bunny delivers the update. Just when things are looking up, Bong-soo reappears on campus, bringing trouble with him.

Bong-soo wrongly assumes Bunny is dating Ji-won, a wealthy chaebol. Driven by jealousy, he confronts her late at night while she’s working on her art piece and violently lashes out. Around the same time, Jae-yol calls Bunny to check in, only to hear her screams. He rushes to her location, but before he can arrive, Bong-soo shatters Bunny’s project and prepares to attack her again—until Ji-won intervenes. Ji-won stops the assault and tells Bunny to call the police. By the time Jae-yol gets there, Bong-soo is already being taken away. Shockingly, Bong-soo refers to Ji-won as “Bunny’s man,” leaving Jae-yol visibly rattled. After the chaos, he walks Bunny home and checks in on her safety.

Time passes, and Bunny and Jae-yol’s relationship continues to blossom. They celebrate their 100th day anniversary, and both seem to be thriving academically. Bunny’s family remains warm and loving, while Jae-yol shares with her that he’s working on repairing his strained relationship with his mother. Bunny encourages him to visit her when he can.

Then, a post about the incident circulates online, claiming Ji-won is Bunny’s boyfriend. The comments flood in with people praising Ji-won’s charm, convinced that the festival’s confession tree brought romance to life. Bunny worries how Jae-yol will react to the false narrative, but he claims he’s fine, even though it clearly bothers him.

As Bunny prepares for her evaluation, she starts staying up late to fix her project. Ji-won offers his help, and the two begin working closely. One night, when Jae-yol and Dong-ha drop by with snacks, they notice how comfortable Bunny is around Ji-won. Jae-yol later tells Ji-won to either return to the U.S. or start maintaining distance from Bunny.

Bunny begins to fear her piece won’t be chosen and that she might lose her scholarship. When she opens up to her parents, they assure her they’ll handle it no matter what. She throws herself into completing her work, with Ji-won frequently by her side. Jae-yol tries to support her too, but his growing jealousy eats away at him. After Bunny forgets to text that she’s home—because her phone died—Jae-yol becomes anxious and decides to check on her in person. Bunny is surprised but happy to see him at breakfast with her parents. On their way to school, Jae-yol expresses his worry, and Bunny promises to always keep him informed.

Still, Jae-yol’s insecurities linger. One night, he finds Ji-won gently draping a blanket over a sleeping Bunny. Upset, he warns Ji-won again, wakes Bunny, and escorts her home. Though she apologizes, the tension simmers beneath the surface.

When evaluation day arrives, Bunny’s project isn’t selected. She’s crushed. Before she can gather herself, she receives a call from her mother: her father lost their family’s savings after falling for a scam by someone he trusted. The news hits Bunny hard, and she begins to question if she’s being selfish for continuing to pursue her dreams.

Meanwhile, Jae-yol receives great news—his team has made it to the next round of a major competition. He calls Bunny to share the excitement, and though she congratulates him warmly, she turns down his invite to celebrate, saying she’s too tired. But Bo-bae and Kkot-nim convince her to go out, inviting Ji-won to join them.

Over dinner, Bunny opens up to her friends about her family’s financial crisis and her worries. Jae-yol, meanwhile, skips his night out and messages Bunny, asking if she’d like to grab dinner. Unaware she’s already out, he’s surprised when his friends spot her at a restaurant. Curious, he asks for the location and heads over.

As the evening wraps up, Bo-bae and Kkot-nim leave first, while Ji-won stays behind to wait for Bunny’s taxi. She starts to doze off, and Ji-won gently lets her rest her head on his shoulder. That’s when Jae-yol arrives—just in time to see the scene. Furious, he confronts Ji-won and tells him to stop crossing the line.