Episode 10 of "Absolute Value of Romance" commences with Eui-ju witnessing Woo-su engaged in a delightful conversation with his female friend. Her jealousy mounts as she observes their intimate smiles and cheerful interactions. E-den, who is present at the scene, also recognizes Professor Nah Deul-i, a Fields Prize-winning mathematician from Princeton and Woo-su's Olympiad companion. Eui-ju overhears the conversation between the teachers, but Woo-su interrupts and escorts Deul-i away, promising to stay in touch.
As Woo-su walks back home, Eui-ju follows him, eager to inquire about Deul-i's personal life, particularly whether there's a romantic involvement between them. Woo-su puts a stop to her inquisitive behavior and threatens to call her parents if she fails to score at least 50 marks in the upcoming Math test.
Meanwhile, Eui-ju buys a bottle of soft drink for her brother and vents to Woo-su about being blackmailed by him over her BL novels. Woo-su questions Eui-ju's determination to become a writer, to which she responds that she wants to do something meaningful with her life and pursue her dream of becoming an author.
Eui-ju then requests Woo-su to continue telling her the story about why he chose the teaching profession. Woo-su looks at her for a moment but suddenly becomes nervous and leaves for home. Back at the teachers' house, Gi-jeon, Da-ju, and Dong-ju discuss Woo-su's friendship with Deul-i, while Da-ju and Gi-jeon speculate about their relationship.
That night, Eui-ju writes a new chapter of her story, introducing Deul-i as a character. In the chapter, Deul-i's character kidnaps Dong-ju's character. Woo-su's character appears and defeats Deul-i's character, saving him.
However, instead of imagining Dong-ju being rescued, Eui-ju found herself daydreaming about Woo-su rescuing her, and her excitement grew with each passing fantasy. The next day, Ji-a arrived late to class with bruises on her hands and the scent of alcohol lingering around her. Woo-su asked for Ji-a to be taken to the medical room, deliberately ignoring the alcohol smell. Ji-a left the classroom but ran into E-den, who immediately took her to Principal Young-hee's office. Together, E-den and Principal Young-hee scolded Woo-su over Ji-a's behavior and tardiness. Woo-su tried to defend Ji-a and asked Young-hee to allow her to remain in school. However, Young-hee remained determined to suspend Ji-a despite Woo-su's protests. On his way out, E-den mentioned Na Deul-i to Young-hee, leaving the principal visibly bothered due to her disagreement with Woo-su despite his friendship with a Fields Prize-winning mathematician.
Later, Woo-su confronted Ji-a and asked her to write an apology letter. He gave her another chance to correct her mistakes and warned her to be more careful going forward. Meanwhile, Go-ya continued to isolate herself from Eui-ju and ignored all of her attempts to make peace. Around the same time, Eui-ju learned about Woo-su standing up for Ji-a at school. Her friends encouraged her to repair her friendship with Go-ya before things became worse between them.
That night, Woo-su reflected on Deul-i's proposal to work on a research project together. He thought about their conversation and decided to go out for a walk. Dong-ju joined him, and the two discussed Woo-su's worsening eye health during their walk. Elsewhere, Eui-ju was forced to step outside to buy a cold drink for her brother. She spotted Woo-su and Dong-ju together and quietly followed them. Eui-ju overheard Dong-ju encouraging Woo-su to accept Deul-i's research opportunity and move to America. The episode ended with Eui-ju asking Woo-su if he was really going to leave.
