In the ninth episode of "DNA Lover," titled "Bad Timing," the narrative delves deeper into the complexities of love, timing, and the genetic predestiny that So-jin holds so dear. The episode commences with Mi-eun, portrayed by Jung Yoo-jin, reflecting on her relationship with Yeon-u, played by Choi Si-won. She ponders the timing of their encounters and the recent stirrings of her heart towards him. Yet, Yeon-u remains blissfully unaware, caught up in the joy of planning a date with So-jin, embodied by Jung In-sun, and relishing their burgeoning romance.
On the day of her discharge, So-jin is touched by Yeon-u's gift of a pair of shoes, and in return, she presents him with a couple's bracelet set. Despite not being the type for such sentimental gestures, Yeon-u conceals his true feelings and assures So-jin of his affection for the bracelet. He even promises to wear it always. Meanwhile, Gang-hun, brought to life by Lee Tae-hwan, arrives to assist So-jin, feigning nonchalance while internally wrestling with his growing affection for her.
In a parallel storyline, Jung-tam volunteers for a gym photoshoot promotion with Sung-mi, and she takes up the challenge to sculpt him into the perfect physique by the deadline. However, the relentless workouts become a source of strain for Jung-tam, leading him to confide in Yeon-u. Yeon-u, in his wisdom, advises honesty, suggesting that if Sung-mi truly cares for Jung-tam, she will understand his struggles.
As the plot progresses, So-jin and Yeon-u's relationship flourishes, with frequent phone calls and sweet dates filling their days. Yeon-u demonstrates his commitment by prioritizing So-jin over a friend's wedding photography event, a decision that leaves Mi-eun disappointed, as she had anticipated his presence.
In a moment of forgetfulness amidst her romantic preoccupation, So-jin overlooks Gang-hun's memorial service. Realizing her oversight at the last minute, she dashes to buy flowers and rushes to the cemetery, leading to the cancellation of her date with Yeon-u. In a twist of fate, Yeon-u's friend's photoshoot and Gang-hun's memorial service occur at the same venue, the latter being the site of Gang-hun's father's wedding photos. While Gang-hun's father requests privacy to reminisce, Gang-hun and So-jin find themselves alone, only to cross paths with Yeon-u, Mi-eun, and other friends.
So-jin's composure crumbles as she witnesses Yeon-u and Mi-eun in matching Hanbok sets, and her dismay intensifies when Mi-eun assists Yeon-u with a gesture that appears intimate. Yeon-u, too, is taken aback by So-jin's cancellation of their date in favor of Gang-hun's memorial, but he assures Mi-eun of his indifference. On their drive back, So-jin admits her discomfort to Yeon-u but reaffirms her trust in him, convinced of his status as her DNA lover.
The following day, Mi-eun and Gang-hun's paths cross at a food stall, where Mi-eun encourages Gang-hun to confess his feelings for So-jin before it's too late. Concurrently, So-jin's anxiety escalates as she notices the attention Yeon-u garners from other women during their dates. Believing it to be a result of his "Indecent Octopus gene," she becomes increasingly fearful and distracted, barely registering Yeon-u's invitation to a movie date.
Mi-eun, unable to shake her thoughts of Yeon-u, seeks So-jin's professional advice under the guise of a consultation. After their meeting, Mi-eun offers So-jin relationship advice, highlighting her own deep connection with Yeon-u and suggesting that he should not be restrained or pressured in a relationship.
So-jin, overwhelmed by Mi-eun's insights and her own concerns about Yeon-u's genetic tendencies, confides in A-ri and experiences an epiphany. Driven by her scientific acumen, she develops a serum aimed at enhancing Yeon-u's genes, specifically to suppress his cheating genes and activate his monogamy gene. She presents the serum to Yeon-u, urging him to use it regularly.
The episode continues with a movie date for So-jin and Yeon-u, where So-jin misinterprets Yeon-u's actions, believing he is about to express his love for her in the car. Her embarrassment in front of Yeon-u adds a touch of humor to their dynamic. Meanwhile, Jung-tam and Sung-mi's date ends in a disagreement over Sung-mi's perceived lack of sensitivity, but the conflict remains minor.
A-ri's storyline intertwines with the main plot as she visits the church to confess her trauma to Father Andrea. She recounts a harrowing high school incident where her friend Yoon-hye was bullied and ultimately killed during a school trip. A-ri, paralyzed by fear, hid in a closet and blames herself for not saving Yoon-hye. Father Andrea offers comfort, absolving her of blame and encouraging her to seek happiness.
In a dramatic turn of events, Yeon-u's parents' relationship reaches a breaking point, with his father suspecting his mother of murder. The revelation deeply affects Yeon-u, who, despite his nonchalant facade, seeks solace in Gang-hun's company, sharing his pain over the divorce. Gang-hun provides support, empathizing with Yeon-u's desire to make So-jin his destiny, despite his skepticism about fate.
The episode culminates in a dramatic morning scene where Mi-eun visits Yeon-u, intending to confess her feelings. Their conversation is interrupted by So-jin's video call, during which she invites Yeon-u to breakfast. Upon seeing Mi-eun at Yeon-u's home, So-jin feigns composure but quickly ends the call, claiming she must go for a run. A-ri and Gang-hun grow increasingly restless as they speculate about Mi-eun's presence at Yeon-u's home.
So-jin's anger is palpable as she defends Yeon-u against A-ri's suspicions, but she cannot hide her true feelings. She storms out into the rain for a run, with Gang-hun in pursuit. Yeon-u, too, races towards So-jin, but she ignores their calls and switches off her phone.
In a heart-wrenching moment, Yeon-u finds So-jin first and confronts her anger, promising to explain everything. He asks for her trust in his feelings for her. As they embrace, Gang-hun watches from afar, feeling dejected. This marks the third time Yeon-u has reached So-jin before Gang-hun, leading him to reflect on his perpetual tardiness in expressing his feelings for So-jin. He drowns his sorrows in alcohol and revisits the park where they met as children, filled with regret and resignation.
"Bad Timing" is a poignant exploration of the intricacies of love and the role that timing plays in the fate of relationships. It is a tale of missed opportunities, unspoken feelings, and the genetic bonds that So-jin believes dictate the course of true love.