Friends to Lovers / Close As Family to Lovers

Close friends for 8 years. 

Friends since high school.

Episode 3 - 5

Enemies --> frenemies --> friends --> lovers

Leads have been friends on and off since they were six.

The ML and FL were head boy and head girl of the same class in high school. As the boys and girls often disagreed, they were often put in the position of rivals but the ML already liked the FL at this point. However, after a boy in the class pretends to like a girl in the class to trick and manipulate her, the FL becomes very distrustful of mens' romantic advances. The ML doesn't confess his feelings to the FL but instead starts to become her friend. He intentionally goes to the same university as the FL where they become best friends. The ML's feelings for the FL remain, but they are never single at the same time.

Leads become friends while protecting a secret.

Friends since early childhood. The ML studied abroad.

Enemies --> friends --> lovers

ML had a crush on the FL in elementary school. They don't recognize each other at first when they meet again in university and start up a light-hearted rivalry / teasing friendship. 

The ML and FL grew up next door to one another. The FL confessed her feelings when they were in high school, but he rejected her. Over time they became friends and he came to also have feelings for her, but was too shy to confess. The story follows them through university and into their working lives. 

The FL joins a fight where the ML is outnumbered. They become sworn brothers and then very loyal friends. 

Their parents were best friends and the ML and FL were inseparable friends when they were little kids before a tragic event intervened.

The FL had to look after the ML on her mum's behalf when they were little kids and they had a part-babysitter part-sibling relationship. He developed a crush on her before moving abroad, and vowed to return for her one day. When he returns, he arranges with her mum to live with the FL. His memories of their time together are sun-kissed, her memories are not. Once she knows who he is, she treats him like an annoying little brother and they have a familiar, family-like relationship.

The ML is the younger brother of the FL's best friend. His mother died when he was young and his father got remarried and moved abroad, so he and his sister are treated as part of the FL's family. The ML works abroad for three years, and when he returns he works in the same building as the FL.

ML and FL were friends in elementary school after the FL helped the ML. He developed a crush on her before moving abroad. They kept up a correspondence but eventually fell out of touch before he moved back to Korea to find her.

Leads are the same age and are not related by blood, but due to complicated circumstances they lived as niece and uncle under one roof from when they were kids.

Enemies --> friends --> lovers