In the fifth episode of XO Kitty's Season 3, Kitty wakes up from a nightmare where Min Ho is making out with Eunice. She confides in Yuri, who tries to calm her down. Yuri receives a message from Yisoo asking to meet and says she will attend the opening of Dae's father's restaurant later that evening for Chuseok.
On her way to class, Q tells Kitty that he and Jin have confessed their love for each other. He says Marius is no longer a concern, but admits he is nervous about Jin meeting his mother at the restaurant. Kitty reassures him that Jin will make a good impression.
Kitty goes to Min Ho's dorm room to talk about the previous night. She brings up seeing him hug Eunice, and Min Ho gives her a necklace, saying Eunice helped him pick it. Kitty accepts the explanation and asks him to invite Jiwon's grandmother to the restaurant opening.
Meanwhile, at work, Yisoo asks Yuri to take care of her dog, Koko, while she travels. With no one else to leave the dog with, Yuri brings Koko to the restaurant and plans to keep her hidden from the guests.
At the restaurant, Q's mother meets Marius and speaks dismissively about Q in front of Jin. Q tries to stop her, but she continues. Jin steps in and defends Q, which leaves the table tense but means a lot to him.
Elsewhere, Kitty tells Jiwon that she invited Halmoni as a surprise. Jiwon reveals she is not on good terms with her grandmother after moving to Seoul against her wishes. The situation escalates when Halmoni arrives and the two argue, causing Jiwon to leave. Kitty apologizes, but Jiwon says it will not fix things.
Back at the main event, Dae and his father raise a toast to his mother as they celebrate the restaurant's opening. The group gathers for the occasion, marking Chuseok together.
Later, Eunice arrives but is surrounded by paparazzi. Min Ho helps her get inside without drawing attention. Inside, Eunice compliments Kitty's necklace, which makes Kitty realize Min Ho was not honest with her. The episode ends with Kitty feeling confused and hurt by Min Ho's actions.
Meanwhile, Yuri notices that Koko is missing and embarks on a search for the dog. Outside, she overhears Eunice confiding in Min Ho about her fear of discussing her situation with her parents. Juliana rescues Koko and returns her to Yuri. Yuri takes Koko to the bathroom where Kitty is hiding. The dog discovers a positive pregnancy test in the trash, and the two put the pieces together. Kitty deduces that Eunice is pregnant with Min Ho's child and believes that's why he lied.
That night, Kitty confronts Min Ho, accusing him of lying about not being with anyone over the summer. She refuses to listen to his explanation and walks away. Elsewhere, Kitty runs into Jin and inadvertently reveals that Q had sent Marius an inappropriate photo over the summer. Marius's provocation leads to a fight between Jin and Q, with Jin's punch accidentally hitting Q before she leaves.
Q is upset with Kitty for exposing the truth and asks her to stay away from him. On the drive back, Q's mother apologizes to him for not appreciating him earlier. Back at the restaurant, Dae reveals to Kitty that he was the one who hooked up with Eunice over the summer. He suggests that if Eunice is pregnant, the child could be his and not Min Ho's. He also reveals that Min Ho did not know he joined the tour, making Kitty realize she had misjudged him.
Later, Dae speaks to Eunice and says he will support her decision regarding the pregnancy. Eunice admits she is not pregnant and that her missed periods were due to stress. She also shares that she's struggling with the attention that comes with being in the spotlight.
Kitty tries to apologize to Min Ho and admits she was wrong to doubt him. Min Ho remains upset and says he's tired of trying to earn her trust. He ends their relationship.
The episode ends with Kitty calling Lara Jean to tell her about the breakup, after which Lara Jean books a flight to Seoul to be there for her.
