What about the friends who discover they want to date? Is it believable?
Beauty and the Beast is supposedly the quintessential example of this: friends followed by passion. However, with few exceptions, nearly every "Beast" I've seen or
read about is bursting with animal magnetism (quite literally): it's
never entirely believable that Beauty felt nothing until she said, "I do."
There's a writing problem here. In contemporary romances, the reader starts thinking, "Seriously, these two friends NEVER thought about the possibility of dating? It just kind of struck them NOW?"
It's an attractive notion, in large part because it allows for a narrative arc while explaining away the lack of a prior relationship. (If the couple did previously throw out the idea of dating, it is difficult to shake the unsettling notion that one friend is now settling or taking advantage: All my other relationships stank. You'll do.)
However, there are a few narratives with this approach that work:
Chandler and Monica: Yup, I found their relationship believable for several reasons. For one, they met each other during Monica's teen years. Chandler's few extra years in age and Monica's self-consciousness over her weight established Chandler in the role of "Ross's college friend," and roles can be quite powerful. They are good friends when the show begins AND (from a writing point of view) the writers prepare us for their eventual relationship. It was a surprise but not a total surprise.
Beauty and the Beast does work--it just doesn't work as effectively as romance lovers like me like to believe.
Orlando and Jonti from Cochrane's Cambridge Fellows Series: Orlando is a kind of Sheldon figure. It takes awhile for his body to get on board with his mind.
One variation of friends to lovers is "Not friends but knew each other because you're my best friend's younger sibling" (see Monica and Chandler)--I'll save that trope for another post.