I tried reposting it in another post, but it didn’t let me comment after I edited it.

This is the book summary. Sorry if there are mistakes; I tried my best. 

The two girls meet when Kim’s family moves next door to Wan’s family. Wan has been dreaming about a girl since she was young and realizes Kim is the girl in her dreams. Wan finds out that her dad is strangely close to Kim's dad. It happens several times, and Wan figures out they are lovers. The two Dads run away together, leaving their daughters and wives behind. Some time passes, and when they go back to school, rumors emerge about the two fathers running away together at their school. Wan tries to get close to Kim, but she ignores her and tries to avoid her at all costs. Wan wants to be close to someone who can understand the pain of their father leaving, and Kim is that person. 

They eventually get close, but Kim and Wan make it clear they are not friends. Wan and Kim have dreams of each other, and they do romantic things in their dreams. Some of this affects their real life because if they fight in real life, they make up in their dream world. The four friends get closer as time goes by. They have a lot of tension in their friendship. They have feelings for each other but neither of them wants to confess. Also, Kim doesn't like same-sex relationships because of her trauma of her father abandoning them for Wan's dad. This is why Wan is even more afraid to confess her feelings towards Kim. Wan, in school, one day, says that whoever is the first person to give her a gift, she will date them. After school, Wan checks the bag for the gift to see who gave it to her but cannot find it. Mon, one of the friends in their group, makes some time to talk to Wan alone. She tells Wan that another student at school saw Kim throw away the gift given to Wan on Valentine's Day! Later that day, she gifts a drawing of Wan sleeping to her ☺️ Mon (the friend questions Dawan if they like each other and asks her if Kim gave her a gift, and Dawan denies it ). 

Dwan is planning to tell Kimhan her feelings. In chapter 19 of the book, as she heads home for dinner, she finds that her mom is not home. So she checks to see if she's at the neighbor's house, Aunt Aey’s (Kimhans mother). She finds an unexpected scene. She sees her mother and Aunt Aey kissing each other. She keeps it a secret. This prevents Dawan and Kim Han’s romantic relationship from progressing. Wan finds it impossible to confess now because both of their father had an affair and ran away together. Now, their moms are also in love, and Kim and Wan love each other. She finds it too much to bear and doesn't want Kim to find out and get hurt again. The four friends make a time capsule where, in 10 years, they will open the letters they wrote to each other. Kim and Wan write letters, confessing their feelings to each other, and leave them in the time capsule. 

Time passes by, and Dawan becomes a famous actress. Kim works for her, and they protect each other and live together in a condo. Dawan insists they live together to prevent Kimhan from discovering the truth about their moms. Dawan knows her mom and Aunt Aey suffered after their husbands left them and doesn't want to separate them because she knows they are in love. Wan doesn't want to take her mom's happiness away. Eventually, Kimhan meets a man named Mawhin. Kim introduces Mawhin to Wan as her boyfriend. She is jealous but cannot complain because she has had boyfriends in the past as well. The difference is that when Wan went on the dates with her ex boyfriends, she takes Kimhan along with her on her dates—leaving the boyfriends as the third wheels🤣. Wan's ex-bfs always gave her an ultimatum to choose between them (Wan’s bf’s) and Kim. Dawan always chose Kim, and her boyfriends broke up with her. Wan has never slept with her ex-boyfriends, and when they tried to get her drunk to have sex with her, Kim always rescued her. Mawim Wants to marry Kim Han. Mawhin has a conversation with Dawan, asking her if he should go ahead and ask Kimhan to marry him. Mawhin wants to know if Dawan has feelings For Kim, telling her that he knows how Kim feels for her and wants to see if Dawan also feels the same for Kim. Making sure he can safely propose to Kim with out Dawan getting in the way. Mawhin asks this in an indirect way. Dawan understands, but she is still in denial or doesn't dare to confess the truth about her feelings for Kim. It's finally Time to open the time capsule. Wan goes before the friend Groups goes together to retrieve the time capsule. She secretly steals the letter she wrote, confessing her feelings for Kimhan. When all the friends go retrieve it, Kim hands the letter to Wan. Days pass, and Wan still does not dare to open the letter Kim wrote to her 10 years ago. Kim calls Dhawan and asks if she read the letter, and Wan says yes and asks what she thinks. (But Wan still has not read the letter) Kim wants to know what she thinks. Dahwan responds she has no opinion on it. So before Kimhan ends the call, she goes silent and tells Wan, “It's time for me to let go”. On Kim's wedding day, Wan finally reads the letter. It reads: 

A Dahwan, If you're reading this, it means ten years have passed. I've spent a long time contemplating whether I should write to you about this. But by the time you read it, ten years will have gone by, and we will probably laugh because we will have grown and matured. 

Among all my friends, you are the one I love the most. You are the best person who will always hold a special place in my heart, and no one can replace you. If I were to tell you that we were so close that I dreamt about you, would you think it's strange? I saw you even before we became friends. 

In my dreams... 

For as long as I can remember, I've had a friend in my dreams. It's a completely blue and white world. There's a big tree and a river, and the surroundings change over time, though I don't know why. I never knew if you truly existed. Every time I woke up, I would forget who that friend was. 

Until we met in reality. That girl from my dreams turned out to be you. 

We did many things... Ah, I don't know how to put it into words. Let's just say they were very good dreams. Every time I dreamt, I didn't want to wake up. But if I didn't wake up, I would regret not being able to go to school and come home to you, just like we do. 

You were always with me. And now, it turns out that you're always in my thoughts and in my heart. You're a friend, a big sister, a little sister, and sometimes a pain in the ass. But I love everything about you. 

I think I'm in love with you... Even though I don't like deviating from heterosexuality because of our parents, you are my exception. I love you for who you are. I don't care if you're a man or a woman. But I don't know if, after ten years, when this letter is opened, I will still feel the same.

 If either of us already has a lover, read this letter and laugh awkwardly with each other.

But for now, as I write this letter, this is how I truly feel. And if what I feel in ten years is still the same, and you feel the same way, let me know. 

Dhawan, I dream of you.

End of letter. 

After Dhawan reads the letter, she rushes to Kim's wedding ceremony and enters the room where Kim is getting ready for the ceremony. Dhawan tells her, “Kim Han, I also dream of you”! They confess to each other their love. Just as the wedding is about to start, paparazzi and new stations are waiting for the couple to get married. Wan takes and escapes with Kim together. They run away to a hotel, And Kim and Wan spend the wedding night together. News goes out to the public that a famous actress took the bride and escaped with her, embarrassing the rich groom. 

There is more to the story, but they have a happy ending