Episode 1 of "Crushology 101" kicks off with Bunny's narration, weaving a tale of her lifelong fascination with handsome men, illustrated through nostalgic flashbacks of her swooning over gorgeous guys at various stages of her life. Now a talented sculpture student at Yein University, Bunny introduces us to her current beau, Ko Bong-soo, much to the mild astonishment of her friends, Nam Kkot Nim and Kwon Bo Bae. Their curiosity piqued, they wonder how this seemingly mismatched pair came to be.
The story unfolds: Bong-soo, relentless in his pursuit, wore Bunny down until she agreed to give him a chance, driven by the belief that what truly matters is whether a guy likes her for who she is. Besides, she had grown convinced that handsome guys were simply not interested in her. Regardless, Bong-soo emerged as a doting boyfriend, always striving to bring joy into Bunny's life. The next day, he presents her with a pearly necklace, but before he can adorn her with it, a dashing figure bumps into him, narrowly sparing the necklace from harm. Bunny, charmed by the gesture, beams with appreciation.
Meanwhile, Yein University welcomes a new face, Cha Ji-won, who enrolls in Bunny's department. We also encounter another attractive student, Hwang Jae-yeol, and his entourage. Post-lectures, Bunny dials Bong-soo's number, only to be ignored. However, when a call from a friend comes through, Bong-soo eagerly picks up, slipping and inadvertently pressing the live broadcast button in the studio. In an unplanned on-air moment, Bong-soo reveals his true intentions in dating Bunny—solely to consummate their relationship, with an overnight trip planned as the culmination.
Gasps ripple through the crowd, but Bunny's fury is palpable. She confronts Bong-soo, punching him when he attempts to shift blame, and publicly ends their relationship. Amidst the stunned studentry stand Ji-won and Jae-yeol, witnessing the dramatic scene.
Humiliated and heartbroken, Bunny flees but eventually returns to drown her sorrows with her friends, vowing to date only handsome men henceforth. The morning after, Bunny informs her parents of her intention to take a leave of absence from school. Though they try to persuade her otherwise, they are no strangers to her threats, having seen her change her mind once before when a handsome neighbor moved in. They hope that a handsome student at school might sway her decision once again.
Fortunately, Bunny bumps into Ji-won at school, and upon laying eyes on him, her resolution wavers. She guides him to the library and strikes up a friendship with him. Sooner rather than later, Ji-won stumbles upon Bunny's statue and crosses paths with Jae-Yeol. An instant dislike sparks between them, exacerbated by their subsequent encounter that leaves an unsavory taste. Ji-won finds Jae-yeol's demeanor undeniably offensive.
As the afternoon unfolds, Bunny catches sight of Jae-yeol and his cronies, who are joyfully conversing after wrapping up a project for a competition. Jae-yeol loses his footing, prompting Bunny to rush to his aid. However, her timing is off, and she inadvertently pushes him just as he regains his balance. In the ensuing chaos, Jae-yeol's tablet slips and shatters. Tempers flare as their project data was stored solely on the damaged device and hadn't been submitted yet. Bunny pleas for forgiveness and vows to reimburse Jae-yeol in installments. Following their accord, they hastily exchange phone numbers.
In the twilight hours, Ji-won attends the freshman initiation and is paired with Bunny. Their initial interactions are promising, quickly blossoming into a camaraderie. Bunny's astonishment at discovering Ji-won's chaebol status amuses him, while he finds her endearing. To assist Ji-won, who is unfamiliar with alcohol, Bunny offers to toast in his stead. In gratitude, he promises to treat her to a meal soon.
Meanwhile, Jae-yeol finds little solace at his department's initiation party, his mind preoccupied with the tablet and their project. Seeking respite, he excuses himself for some fresh air and catches sight of Bunny reveling at the initiation bash. Noticing him, she stumbles outside to converse with him. By this point, her intoxication is evident, leading her to label him a jerk before complementing his handsome features, promptly followed by an unceremonious vomiting episode all over him.
The subsequent morning, Jae-yeol tends to his laundry while concocting a plan for revenge against Bunny. Later at school, he attempts to engage her in conversation, but she dashes away. He gives chase, their pursuit culminating at a school event outdoors. Bunny spots Ji-won and tries to conceal herself behind him. Jae-yeol spots her and pulls her towards him, resulting in a tangled fall that somehow lands Jae-yeol atop Bunny.
