Ever notice how fairytales and about ninety-nine out of a hundred romance tales you see or read are about how two people first got together? Cinderella meets her prince, against all odds, and he manages to find her again after he's lost her, against all odds, and the two of them ride off together in the carriage, into the dusky sunset. Prince Charming defeats the evil dragon to free Sleeping Beauty from her hundred-year slumber. Belle falls for Beast despite his unsavory appearance.
How come we don't start the story with Cinderella five years into her marriage with the prince? Why not pick up a decade after Sleeping Beauty woke up and Prince Charming and she made castle together? Why do we never see Belle and Beast after they've had their first couple of half-human, half-animal offspring?
It's because there's nothing exciting about that. We don't care about two people that've been together for years; that's old news. We want to know about the new and exciting things that are going on: those two people who might get together – who should get together – but who still may not get together.