The sixth episode of Dear X commences with Ji-sun's surprise arrival at Joon-seo's abode, only to find Ah-jin already there, wearing Joon-seo's shirt. Ah-jin asserts her presence due to Ji-sun's meddling in her professional endeavors, prompting a scuffle between the two. Joon-seo intercedes, preventing a full-blown altercation.
At work, Ah-jin engages in a romantic scene with In-gang. Post the shoot, In-gang requests a private conversation, sharing the tale of his rise to fame. It all began with a band, but his ascendancy was fueled by an incident where his junior, Ji-hyeok, had an allergic reaction after consuming a macaron with nuts. Despite knowing the contents, In-gang did nothing, leading to Ji-hyeok's demise and subsequently, In-gang being granted an MC role that catapulted him into the limelight. Now, he is haunted by remorse every time Ji-hyeok's texts wish him well. In-gang then reveals that he saw Ah-jin's video with Le-na and believes she can reach the top without the assistance of such nefarious means.
That evening, Detective Park calls Ah-jin and issues a threat; he demands a meeting and warns her that this is her future if she doesn't comply. Ah-jin follows the address and arrives at a VIP room in a club filled with drugged and disoriented patrons. Detective Park reveals this as her future and plots to ruin her life. As she leaves, In-gang intercepts her, leaving her unable to explain her presence there.
Meanwhile, Jae-oh embarks on a new job working with a man who conducts background checks on individuals. Jae-oh's first assignment is to uncover information on Detective Park. Could this private investigator be the same one Le-na hired? Jae-oh follows Detective Park and clones his phone, only to panic when he overhears Park discussing Ah-jin's alleged involvement in her father's death with a reporter. Desperate, Jae-oh calls Joon-seo for answers. Joon-seo reveals that Ah-jin didn't kill her father; instead, Park tried to frame her. They decide to work together to uncover the truth.
Jae-oh visits Joon-seo's residence where he reunites with Ah-jin. They catch up and Joon-seo watches them laugh together, a rare sight of joy in their otherwise tumultuous lives. As she departs, Jae-oh questions Joon-seo about allowing him to meet Ah-jin, knowing Joon-seo's feelings for her. Joon-seo responds that Ah-jin might have a normal life with someone like Jae-oh.
The two men delve deeper into In-gang's story, revealing a heart wrenching tale of guilt, depression, and alcoholism. His past loss of parents at an early age has left him close to his grandmother, whose diary Jae-oh sneakily obtains and presents to Ah-jin. The latter, with a cunning plan, uses the diary's mention of a temple to gain entrance to the old lady's life.
Ah-jin also arranges for Hyang-i a new apartment in the same complex, using the pretext of distributing rice cakes in her name to befriend the grandmother. The old lady recognizes her and even invites her for a meal from her daughter's memorial ceremony. When In-gang learns of this, he is furious, pulling Ah-jin out and warning her to stay away. Ah-jin accuses him of self-inflicted misery and pushes people away, calling him a coward before leaving.
Back home, Joon-seo questions Ah-jin about her plans with In-gang, to which she replies that she needs him to reach the top. After the memorial ceremony, even In-gang's grandmother tells him to stop pushing people away. He breaks down into tears as he gets into his car, watched by Ah-jin with a hidden camera.
Ah-jin then manipulates one of In-gang's men to set up a meeting at Ji-hyeok's café. There, Ji-hyeok reveals the truth to In-gang—that he knew there were nuts in the macaron before eating it and that In-gang was aware too. He tells In-gang that he wanted to quit the industry anyway and that In-gang shouldn't feel guilty anymore. Ji-hyeok also admits that it was Ah-jin who spoke to him and encouraged him to speak to In-gang. Frustrated, In-gang goes to see Mi-ri, telling her he wants to stay away from Ah-jin and also making her officially break up with Le-na.
Meanwhile, Jae-oh and Joon-seo kidnap Detective Park and threaten him with a report about his daughter doing drugs in the US. Detective Park texts the journalist, Reporter Lim, that there is no story. Jae-oh and Joon-seo also discover that the reporter is Le-na's cousin, hired to dig dirt on Ah-jin.
In-gang's grandmother, with a heartfelt apology for her grandson's behavior, encounters Ah-jin. Her eyes linger on Ah-jin, filled with concern and a touch of regret. She inquires about the reason behind Ah-jin's tears during the memorial service. Ah-jin reveals that bomdong, her mother's favorite dish, was also one of the grandmother's favorites, as revealed in the latter's diary.
In a gesture of redemption, In-gang apologizes to Ah-jin and extends an invitation for dinner. Ah-jin accepts, but not before calling Jae-oh and requesting a favor—to ensure In-gang's tardiness to their dinner date. Jae-oh obliges, causing a minor mishap with In-gang's car and even dropping his phone in the gutter.
As Ah-jin waits patiently at her table, In-gang hails a cab and then runs the rest of the way to the restaurant, his breath heavy and his heart pounding. When he finally arrives, he sees Ah-jin just as she is about to leave. The sight of her waiting so long touches him deeply. As she wraps her scarf around him, he leans in and kisses her, their connection renewed.
Elsewhere, Joon-seo meets Le-na for a few drinks. Overhearing a couple of men trash talking Ah-jin, Joon-seo takes offense and starts a fight, only to end up badly injured. The episode ends with Le-na trying to coax him into responding, her concern evident in every word and gesture.
