Boy meets girl, girl dumps boy, boy and girl realize they're made for each other as sappy music swells into the happily ever after. Since everyone already knows how the story ends, the challenge with "rom-coms" is keeping your audience engaged and guessing. The trick: crafting a fierce tug-of-war between 1) the magical attraction or "rightness" of the couple that makes you root for their union, and 2) seemingly insurmountable obstacles that stand in the way. Sometimes these obstacles are external (one character is a "beast", lives across the country, or occasionally turns into a mermaid). But more often love is stymied by internal flaws—commitment problems, selfishness, insanity—which produce plenty of laughs and a wonderful character arc from frog to prince.

Throw in a "cute meet" (a memorable moment when your protagonists first cross paths), a distracting Mr. or Ms. Wrong (who helps reveal just how right the real love interest is), and a sidekick buddy who prods the protagonist toward his or her heart's desire, and you'll have a script worth falling in love with.