I’m writing a romantic movie, but the last days I have been thinking if the story is credible or not. What do I have to do to write a credible romantic story?
— Stefano Vettorazzi Campos
You have to make us care whether the two lead characters end up together, which is really two requirements:
Characters we give a shit about. They don’t need to be likable, necessarily, but they need to be compelling. We need to be curious about what they’re going to do next.
A credible reason to keep them apart. This could be almost anything — war, prejudice, a sinking boat — but if we don’t buy it, you’re toast.
I’d argue that #2 is actually more important than #1.
Cast some attractive actors and we’ll want to see them kiss. But I get angry watching romances in which the hurdles are set too low. If there’s nothing stopping the characters from running off to live happily ever after at the midpoint, why bother?