Episode 4 of Absolute Value of Romance begins with Eui-ju, as she heads to the library. She confides in Dong-ju about her issues with Woo-su, but he defends him. Eui-ju decides to vent her anger through her story by writing a scene where Gi-jeon's character punches Woo-su twice. She finalizes the chapter and publishes it online before calling it a day.
Meanwhile, at dinner, Woo-su takes medication due to his growing discomfort. Dong-ju informs Gi-jeon that Woo-su's spectacles are customized and take time to be delivered. Back in his room, Woo-su struggles to concentrate while trying to work. The next morning, the teachers find him vomiting, and he says he cannot go to school.
In class, Eui-ju learns that Woo-su is unwell and starts blaming herself for taking his glasses. Over the day, she overhears Ha-su speaking to him and realizes how much he is suffering. After school, Eui-ju sees Gi-jeon and Dong-ju searching for the glasses. She realizes her mistake and rushes to the trash to find them. She spots the garbage truck leaving and chases after it on a bicycle.
Eui-ju stops the truck and begs the man to let her search through the trash. She cries while going through it and eventually finds the glasses. She takes them back with her. That night, Eui-ju asks Eui-do to return the glasses to Woo-su. Woo-su recognizes him and realizes the truth. He scolds Eui-ju for lying, and she apologizes in tears.
Woo-su forgives her but tells her she must repay the cost of the glasses. He gives her a daily to-do list and asks her to attend extra Math classes. Meanwhile, Eui-ju returns home, still affected by the situation.
Later that night, she logs in to update her BL story and notices it has gone viral. She is shocked by the number of likes and comments. The response motivates her to continue writing. She writes a new chapter where Dong-ju's character pushes Gi-jeon's character. She adds Woo-su's line about repaying the debt and builds a romantic angle between the characters. Episode 4 ends with Eui-ju continuing her story.
