Because This is My First Time Being Thirty

It’s Ji-ho’s 30th birthday and the worst day of her life at the same time. She becomes homeless overnight as her roommate younger brother wants her pregnant girlfriend to move in. Meanwhile, Se-hee is looking for a new housemate who can follow a certain set of rules.

Because This is My First Kiss

The morning after Ji-ho kissed a total stranger, she wakes up to find out that her new housemate whom she thought was a woman is actually a man. Rather than the fact that they kissed, Ji-ho and Se-hee are sad that they can’t live under the same roof as they are opposite genders.

Because This is My First Proposal

When Ji-ho gets proposed by Se-hee, she becomes confused as she doesn’t know what his intentions are. Sang-goo reunites with Soo-ji, but Soo-ji has no recollection of what happened before.

Because This is My First Marriage

Se-hee and Ji-ho decide to get married, so naturally, Ji-ho introduces her boyfriend to her family. Se-hee must impress Ji-ho’s patriarchal father in order to get his approval. Meanwhile, Won-seok tries to make up with Ho-rang by getting her the sofa she wanted.

Because This is My First Promise

Ji-ho and Se-hee’s parents meet each other for the first time. Although Ji-ho and Se-hee agreed on not holding a wedding, Ji-ho’s mom and Se-hee’s dad think otherwise. Won-seok still can’t understand why Ho-rang got mad.

Because This is "Our" First Time

After the wedding, Ji-ho feels like she and Se-hee have gotten closer. Won-seok and Ho-rang run into each other at the wedding. Meanwhile, Sang-goo gives Soo-ji a piece of his mind when he sees her being mistreated.

Because This is My First YOLO

Bok-nam helps Ji-ho get a job at the café he works at. Even though Ji-ho tells him that she’s married, he keeps coming onto her. When Se-hee sees the two together, he becomes jealous without even realizing. Meanwhile, Ho-rang comes up with a plan to make Won-seok husband material.

Because This is My First Husband

When Se-hee learns about how Bok-nam got reported on the dating app, he looks into it with great interest without letting Ji-ho know. Sang-goo visits Soo-ji at a café near her office, but she acts cold towards him. Unaware of Bok-nam’s intentions, Ji-ho agrees to drink beer with him.

Because This is the First Time I Belong Somewhere

Se-hee saves Ji-ho from Bok-nam. When the two get back home together, they have an honest talk. Ji-ho, Soo-ji, and Ho-rang go to a get-together between school friends.

Because This is My First Time Having In-laws

Ji-ho starts developing feelings toward Se-hee and feels happiness from being able to see him every day. However, it does not last long as Se-hee’s mother pays a surprise visit. Meanwhile, Sang-goo cannot resist Soo-ji.

Because This is My First Beach

Se-hee takes a day off from work for the first time and goes to Namhae in order to help Ji-ho’s family with making kimchi. When Soo-ji finds out that his colleagues at work made a bet about her, she becomes furious. Before leaving to go see Se-hee, Ji-ho finds a poetry book that belongs to him.

Because This is My First Desire

After their first kiss, Ji-ho and Se-hee come back home and say goodnight in front of each other’s bedrooms before going to sleep. For the first time in her life, Ji-ho feels a strong desire lurking inside her. Won-seok feels like something is off between him and Ho-rang. Meanwhile, Se-hee and Ji-ho go on their first date.

Because This Is My First Time Visiting Your Room

Soo-ji gets mad at Sang-goo for invading her privacy, and Sang-goo tries to understand her. The friends find out about how Won-seok broke up with Ho-rang. Meanwhile, Ji-ho gets a job offer from a production company.

Because This Is My First Confession

Se-hee runs into Jung-min. When Ji-ho meets Jung-min the next day, she asks about her past. Se-hee comes to realize that he is only worried about Ji-ho and that he has gotten over Jung-min. Meanwhile, Soo-ji takes Sang-goo’s advice and confronts her abusive colleague.

Because This is My First Intermission

Se-hee accepts Ji-ho’s suggestion to terminate the contract. Won-seok and Bo-mi go to a restaurant together and run into Ho-rang. Trying to ease the pain, Se-hee drinks until he passes out.

Because This is My First Life

After Ji-ho moves out, Se-hee sells his house. Bo-mi tells Won-seok about her feelings and Soo-ji starts her own business. Will Se-hee and Ji-ho end up getting a divorce?