Happy Valentine's Day! I hope you're snuggling up with something (or someone) steamy and dreamy!
Trope: Star-Crossed Lovers
Description: Our heroes are madly, passionately, unbelievably in love...but fate is keeping them apart. There are any number of contributing factors to why they just can't be together and live happily ever after. Some have a basis in reality, like a long-distance relationship or a meddling parent. Others involve concepts such as destiny and luck (and mileage varies as to whether you believe in that sort of stuff).
Examples: Romeo and Juliet, Guinevere and Lancelot, Catherine and Heathcliff from Wuthering Heights
Pros: Oh, the drama! We root so hard for the couple to be together and cheer on their love! When they're forced apart, we cry with them. Shaking our collective fist at the universe for being so cruel can be cathartic, after all.
Cons: If they're truly star-crossed lovers, there's not going to be a happy ending. Done well, the audience enjoys being taken along for the emotional ride. Otherwise, there's a high possibility for disappointment.
Would/Did I Use It?: Again, as this trope is technically defined by the story's ending...well, I'm not going to give away spoilers to my writings. That would just be wrong. (Hey, it's Valentine's Day, I'm allowed to be coy and have a little fun of my own, right?)