Episode 3 of My Happy Ending starts with a flashback from Ah-rin’s birth when Jae-won wakes up in the hospital room. She sees Soon-young awestruck, looking at their newborn baby and joins him.
The episode moves back to the present day, where Jae-won drives to work in a rush. Her brain runs amok, thinking about Soon-young introducing Ah-rin to his mistress. She manages to get to work and puts on a brave face in front of their clients. Soon after the meeting ends, Jae-won goes to meet Su-kyeong. She tells her psychiatrist how she was gobsmacked after learning about Soon-young’s affair as it wasn’t something she expected from him.
That night, Soon-young comes home from work and finds Soon-young waiting for her. Soon-young asks about her day and tells Jae-won that he will resume his job as a professor from the following semester. Jae-won tells him that the couples retreat they were scheduled to attend is cancelled after one of the couples recently broke up.
She claims that the male counterpart of the couple cheated on his wife, leaving the woman to get a divorce. Jae-won hopes to trigger a reaction from Soon-young from the mention of cheating but he is rather calm. She confronts Soon-young directly and wonders what he would do if their family were to go through something like this.
Just then, Ah-rin shows up and takes her mother to her room for her to play with. Jae-won asks Ah-rin what she did all day and the little girl claims that Soon-young took her to meet his friend. She adds that they were not able to meet the friend because the person they were meeting was busy.
That evening, Tae-oh runs into Yoon-jin and takes her over to his studio for a chat. There, he talks to his senior about Jae-won’s recent doubts and confronts Yoon-jin about her affair with Soon-young. Yoon-jin states that she was not dating Soon-young but was with his twin brother – Heo Chi-young.
At the same time, Jae-won grows suspicious of her husband and hides a spy camera in their living room. Soon-young writes something in his diary but hides it as soon as he senses Jae-won around. The next morning, Jae-won tells Soon-young that Ah-rin will no longer be going to kindergarten and adds that she will be homeschooled moving forward.
She leaves for work without much of a discussion with her husband. Outside the office, Jae-won runs into Yoon-jin but ignores her. Jae-won waits for her former friend by her painting site and the two argue about their respective achievements. Jae-won starts getting a panic attack and leaves the conversation after accusing Yoon-jin of trying to destroy her life.
Jae-won then goes out to see Mr Han, who tells her all about his conversation with the doctor working at the hospital his mother was admitted to. Mr Han reveals that Jae-won’s mother was admitted to the hospital not thrice but four times, all due to pesticide poisoning.
The insurance officer adds that Chang-suk brought Jae-won’s mother in for ingesting the pesticide by accident on all occasions and wonders why the doctors didn’t get the cops to investigate Mrs Jeong’s death. Jae-won drives herself to her stepfather’s house to have a chat with him.
Jae-won recalls an incident from her childhood when a shopkeeper accused her of a mistake made by other children. Jae-won recalls being targeted because of her mother’s recent arrest due to her gambling addiction after being indebted to many loan sharks.
She then purposely destroys one of the toys at the shop out of spite. Chang-suk shows up to pick her up and buys the toy for her. Surprisingly, Chang-suk addresses little Jae-won as Yoon-jin.
Back in the present day, Yoon-jin confronts Chang-suk about the insurance money and learns that Chang-suk confronted her mother for borrowing more money. Their argument ended with Mrs Jeong consuming the pesticide in an attempt to end her life.
Chang-suk tells Jae-won that her mother has a lot of debt and the money procured from the life insurance was used to pay off the debt. He also reveals that he used the remaining money to buy a modest property and adds that he’s ashamed of keeping the fact a secret from her.
Jae-won feels guilty for doubting Chang-suk and is embarrassed to learn that Soon-young was supportive of her stepfather throughout his hospital visits with Mrs Jeong. On the other hand, Tae-oh meets the IT Admin – Mr Yoo and asks him to recover the footage from the home camera he left in Jae-won’s office.
From the footage, the two discover that it is the design team member – Baek Seung-kyu – who attacked Jae-won in her office. Tae-oh talks to Secretary Kim and learns that Seung-kyu is in Jae-won’s hometown. Tae-oh gets in his car and leaves to go to Jae-won’s hometown, trying to call her nonstop.
Jae-won, who had left her phone in her car, has a meal with her stepfather and leaves to go back home. Chang-suk drops Jae-won to her car and then goes back inside only to shatter a photograph of Mrs Jeong. A flashback shows Chang-suk watching as Mrs Jeon writhes in pain after consuming the pesticide.
Back to the present day, Jae-won realises that the brakes of her car have failed. She is about to crash off the freeway when Tae-oh shows up behind her. Tae-oh manages to position his car to absorb the blow from Jae-won’s car, causing her car to stop abruptly.
Jae-won is petrified and recalls the recent life-threatening attacks on her. She asks Tae-oh how he knew where to find her but the design manager refuses to explain anything without knowing the full truth himself. Tae-oh drops Jae-won home and she tells him how she has a hard time trusting anyone at the moment because of the things happening in her life. She thanks him for saving her life and goes back inside, breaking down.
Tae-oh goes back to the office and learns that Seung-kyu has jumped off the Dereve office building, leaving him in a critical condition. Tae-oh takes Seung-kyu to the hospital and waits there until the doctors treat him. At the same time, Soon-young watches Jae-won suffering and asks her to take it easy.
The next morning, a reporter interviews Mr Kwon and asks him about his transition from being a director at Jae-won’s company into being the owner of his new foundation – the Ye-in Art Scholarship Foundation. Mr Han waits in the other room to have a chat with Mr Kwon and notices how he had funded Jae-won’s education for years along with that of Yoon-jin.
Later that day, Jae-won watches the live camera footage from her house which shows Ah-rin playing with Soon-young. She suddenly gets a text image from her stalker reminding her of “that day” from 7 years ago. Jae-won is suddenly alert and suspicious of her staff.
The nurse hands Seung-kyu’s belongings to Tae-oh who is waiting in the hospital. Tae-oh answers a call on Seung-kyu’s damaged phone and the person on the other line asks Seung-kyu to meet him. Tae-oh recognises the voice on the call to be that of Soon-young and grows suspicious about his connection with Seung-kyu.
Later that evening, Jae-won avoids going back home and spends the time in her studio instead. She is about to take her headache medicines but stops and instead tries to sketch. The thoughts of her close friends betraying her continue to race through her mind.
The following day, the Dereve staff gather together for a conference with the reporters where Jae-won is about to talk about the recent developments of the business. Tae-oh watches Jae-won nearly have a panic attack and stops her from addressing the crowd in such a condition.
In her stead, Dereve’s PR manager – Mr Park In-seok – addresses the reporters. Jae-won is upset with Tae-oh for stopping her from attending the conference. Tae-oh notices Jae-won’s restlessness and asks if she has taken her medication. Jae-won meets her psychiatrist and tells her how she had stopped taking the medication because she felt she had grown resistant to the pills. She tells Su-kyeong that she was worried Tae-oh knew she had bipolar disorder.
The next morning, Jae-won gets Ah-rin ready for the day. The little girl asks Jae-won to allow her to go back to school. Jae-won promises to let Ah-rin go back in a few days. Jae-won leaves for work and runs into her neighbor who tells her that Soon-young was not behaving like himself lately. She tells Jae-won about the incident where Soon-young ignored her.
At work, Jae-won looks through the home camera footage to see Soon-young playing with Ah-rin. However, to her surprise, Soon-young shows up at the office to meet her. The episode ends with Jae-won running home to make sure Ah-rin is safe.
This episode really messed with our mind and I am not sure who to trust anymore. It seems like Jae-won could be suffering from symptoms of her mental health issue which is causing her to behave like this. It is also likely that Jae-won was watching old footage of Soon-young playing with Ah-rin and all the doubts were her disease making her delusional.
With that being said, her stepfather seems shady. Also, there is no reason for Tae-oh to be this obsessed with Jae-won. He likely has feelings for her or he is the stalker who is trying to mess with her.
Moreover, the fact that Jae-won was called “Yoon-jin” as a child makes everything further confusing. I am sure we will have more answers as the episodes progress.