Although the movie was produced in 2004 but for some reason, it only showed it in the cinemas in 2005.

S Diary is a deep meaning movie. Jang Hyuk only appeared for around 5 minutes at the first scene being the female lead's 4th boyfriend. He walked away after throwing these words at the female lead:
I feel really stress & pressurize being with you, you know! Love shouldn't be that way! If you can, I'd suggest you go ask all your 3 ex-boyfriends if they had ever loved you.

So the girl was really sad and went home crying. She has a habit of keeping diaries and she'd always jot down whatever that happened between her & her boyfriends. So she took the time and read about her past relationships with the 3 guys. The story then flashed back to her high school days....

1st guy Goo Hyun: She first met him in church. She was singing in a choir while he was the choir's conductor. Apparently she always failed her English in school so she'd gotten her mom to engaged the guy as English tutor and that was how they'd fallen in love. He encouraged her to study hard and get into a prestigious university but alas, the relationship didn't last as he would be furthering his studies overseas...

2nd guy Jang Seok: A beefy, fellow uni school mate, (The show didn't show how they fallen in love, they just got together like that.) They live together and do homeworks together although the girl did most of HIS homeworks. He's quite a miser but he's a great cook and she loves him very much and already regard him as her husband. But again, the relationship took a turn when the guy married someone else for a stable income, living.

3rd guy (Gong Yoo played the role of a younger boyfriend): A boyish, hunky, graffiti/comic artist. By now the female lead had already graduated from uni and in the working society. She would always walk passed this wall on her way to & fro home. One day, she saw her own portrait on the wall, and the artist said, "What do you think? Looks real? I drew it from my memory cos she's always on my mind."

Awww... They got together and also live together. But this guy is younger than her, so she's always doing his dishes, cleaning his house. All he knows is play & fun. Once again, relationship took a turn when she realised she was trying to be young instead of being herself to be with him. This time she left the man.

So story was back to present, she looked up all these 3 ex-bfs. The first guy had already became a priest in a church and told her that their past was a total mistake. The second guy was already married and has 2 kids and told her to forget about him and not to harrass him anymore. The third guy was still clueless about his future and told her, "The reason why u came to look for me is because you miss my body, isn't it?"

That was so utterly hurting. That was too much for her to take, her 4th boyfriend was right, her past 3 ex-bf didn't love her one bit. She vows to get even with the 3 of them and make sure they pay her back financially for all her emotional lost.

Ok la, shan't elaborate how she get even with them cos I personally think it's quite childish too. Nobody will pull those tricks in modern day life.

Nonetheless, the 3 guys paid her back. So, she had the money. She bought stuffs for herself, for her mom. What's next? She was lost again...

A few years later, she became a writer and her book became a best-seller. She had wrote about her relationships with the 3 unforgettable guys of her life.... Sigh...

I teared up at certain parts. Frankly speaking, I felt quite upset after watching this movie. It hurts to know that guys love girls in exchange for sex?

Ultimately when the female lead confronted those guys, each of them do not really love her and the whole movie is basically about her failed relationships.

There wasn't any conclusion nor message at the end of the movie... I wish it showed a more positive light of 'being stronger' and 'learning from experience to become a better person/lover'. But no, there wasn't. I supposed it was meant to let audience feel bittersweet instead?