Episode 4 of "Family By Choice" unfolds with San-ha receiving a phone call from his mother, which he ignores, leading to a somber night where he wakes up the following morning, his eyes puffy from tears streaming down his cheeks throughout the dark hours.
At the breakfast table, San-ha fabricates a tale of diligent studying, his voice laced with a hint of deception. On the bus ride to school, Hae-joon attempts to discourage Joo-won from pursuing a relationship with the anonymous author of her love letter, seeking San-ha's input. However, San-ha remains tight-lipped, his thoughts locked within.
At school, Dal reveals to Joo-won that she has uncovered the identity of her letter's writer: Joon-ho. Later, Joo-won unexpectedly encounters Joon-ho, who boldly asks her out on a date. She agrees, to the observant eyes of Dal, Hae-joon, and a seemingly perturbed San-ha watching from a distance.
Dal and Hae-joon express their delight in seeing Joo-won with a handsome companion, whereas San-ha's demeanor betrays a hidden discomfort. During their date, Joo-won discovers Joon-ho's particular tastes and opinionated nature, which clash with her own.
As night falls, Joon-ho escorts Joo-won back home and makes a insensitive remark about her cheerful demeanor despite her upbringing by a single parent. Joo-won, feeling offended, retaliates by asserting that she has two older brothers and two father figures in her life, upset by his insensitive comment. She firmly informs him to cease all contact.
Joo-won ponders over the misperceptions people hold about her, San-ha, and Hae-joon, unaware of their years-long bond. At dinner, Hae-joon speaks highly of Joon-ho, prompting San-ha to urge caution before making judgments on his behalf. Joo-won arrives, her face etched with resolution, and declares that she will never see Joon-ho again.
The following day, Dal finds himself bewildered by Joo-won's decision to terminate her relationship with Joon-ho so abruptly after their initial date. Joon-ho, contrite, approaches Joo-won with a heartfelt apology, pleading for another opportunity to prove himself. As the other students rally around with encouragement, Joo-won sets a condition: Joon-ho must keep the confidential words he whispered to her at the bus stop a well-guarded secret. Dal, inquisitive, inquiries about the incident, but Joo-won remains tight-lipped, revealing nothing.
Meanwhile, Jung-hee arrives at the school's doorstep, her intentions set on meeting San-ha. Coincidentally, she encounters San-ha on his way out, accompanied by Joo-won. Stepping out of her vehicle, Jung-hee insists on a private conversation with her son. San-ha, considerate, gently urges Joo-won to head back home while he attends to his mother's needs. Jung-hee then proceeds to express her assumption that San-ha must feel neglected by her decade-long absence. This assertion further搅乱了San-ha's emotions. Adding fuel to the fire, Jung-hee mentions her plan to bring her daughter, So-hui, to visit, which only deepens San-ha's turmoil.
Anticipating a potential drama, Joo-won suggests bringing Hae-joon to the restaurant as a backup support for San-ha. However, Hae-joon declines, urging Joo-won to trust San-ha's ability to navigate this complex situation alone. Inside the restaurant, Jung-hee extends an olive branch, willing to forgive San-ha, leaving him utterly perplexed as to the nature of her grievances. Hae-joon, walking home amidst of his mother's departure, is plunged into a whirlwind of emotions, his heart heavy with unresolved pain.
With an unemotional demeanor, San-ha instructs Jung-hee to request her mother to cease contacting him. He offers Jung-hee his best wishes and departs. Joo-won attempts to ascertain San-ha's well-being, but he remains silent during their walk back home. In a moment of distraction, San-ha steps into the path of moving traffic, only to be swiftly pulled back by a concerned Joo-won. As Joo-won bursts into tears, worried sick about San-ha, he calmly reassures her and leads her to a nearby place to eat, trying to ease the tension.
Meanwhile, Dae-wook encounters Jung-hee during his patrol. Jung-hee's mentions of "her husband" and "her So-hui" stir up Dae-wook's emotions. She emphasizes the importance of family unity and reveals her intention to bring San-ha to Seoul, hoping her husband can assist him with his college applications. Enraged, Dae-wook confronts Jung-hee, leading to a heated argument that ends with Jung-hee feeling humiliated as Dae-wook storms off. In his wake, he warns Jung-hee to leave San-ha be, which she reluctantly follows up on.
Jung-hee seeks legal advice, learning that Dong-gu might claim custody of Hae-joon in a potential legal dispute. That evening, during dinner, Hae-joon becomes agitated when Joo-won mentions San-ha's mother's unannounced visits. San-ha tries to defuse the escalating tension, but Hae-joon confronts him, leading to a fiery argument between the two.
San-ha confides in Hae-joon, revealing that his mother harbors unyielding resentment towards him for his sister's passing and urges Hae-joon to refrain from envying Jae-hee. Hae-joon attempts to counter, insisting that Jae-hee is his mother too, but San-ha counters by highlighting the prevalence of toxic family dynamics, citing Dong-gu's own concealed agendas as an example. Meanwhile, San-ha and Joo-won enjoy ice cream together, excluding Hae-joon, who declines, as they discuss San-ha's lingering hope for his mother's return.
Later, Dae-wook reassures San-ha about Jae-hee, assuring him that she pose no further trouble. Elsewhere, Joo-won strives to reconcile with Hae-joon, offering him ice cream as a peace gesture. The following day, Dong-gu's assistant urges him to reach out to Hae-joon, hoping to reveal Hae-joon's true value.
At school, San-ha warns Joon-ho against pursuing Joo-won romantically. Joon-ho remarks on Joo-won's cheerful demeanor despite her motherless state, prompting San-ha to understand why Joo-won has been so distressed lately. Amidst this, Hae-joon engages in a physical altercation with a teammate.
San-ha interventions at the basketball court, urging Hae-joon to let bygones be bygones as a pressing matter concerning Joo-won demands their attention. The subsequent conversation between the two boys, joined by Joon-ho, quickly becomes school gossip. News spreads, prompting Joo-won to rush to their defense, shielding Joon-ho and scolding Hae-joon for grabbing his collar.
Joo-won dismisses the incident lightly, but Hae-joon warns Joon-ho in no uncertain terms to stay away from her. On their way home, San-ha consoles Joo-won about the malicious rumors, advising her to ignore them. Just then, Jae-hee arrives at Jung-hae's restaurant, accompanied by her daughter, adding another layer of complexity to their intertwined lives.
She urges the little girl, So-hee, to address San-ha as "oppa" (elder brother), yet So-hee stands in trepidation, fearful of San-ha's potential response. San-ha, displaying a surge of aggression towards his mother, insists that Joo-won escort So-hee outdoors. In their private moment, So-hee confides in Joo-won that they intend to bring San-ha along with them to Seoul.
Elsewhere, San-ha issues a stern warning to Jae-hee, cautioning her against interfering in his life and urging her departure. Meanwhile, Hae-joon arrives at the restaurant's entrance, astounded to witness Jae-hee's return, specifically for San-ha. Observing San-ha's harsh demeanor towards his mother, Hae-joon gently advises him to show some empathy. However, San-ha flies into a rage, ordering Hae-joon to stay out of their affairs. Despite Hae-joon's efforts to mediate, San-ha becomes increasingly upset, asserting that they are both mere boys who were deserted by their mother, painting a vivid picture of shared abandonment and emotional turmoil.
