Friends to lovers builds romance on a foundation of genuine friendship. The characters already know each other, trust each other, and care about each other before anyone admits to wanting something more. The tension comes from the risk: if they pursue the romantic feelings and it doesn't work, they lose the friendship too. That fear of losing what they already have is what makes the trope so emotionally charged.
Friends to lovers teaches you to write emotional subtlety. The shift from platonic to romantic is gradual and often internal, which forces you to convey desire through small details, lingering looks, and conversations with hidden meaning. It's one of the most universally relatable romance setups because most people have wondered 'what if' about a friend.
Best friends with a ruptured friendship, slowly realizing what they've been to each other all along.
The definitive friends-to-lovers story, asking whether men and women can be friends without desire getting in the way.
While it starts as fake dating, the genuine friendship that develops drives the romantic realization.
Write a scene between two friends where one of them realizes, mid-conversation, that their feelings have changed. Don't have them say it. Show it through a shift in attention: they suddenly notice the way the other person laughs, or holds a cup, or says their name. The reader should feel the moment it clicks.