Although there are sci-fi elements around the edges, few films have as much to say about love, how we remember it and truly feel about it, than Eternal Sunshine of the Spotless Mind
Jim Carrey and Kate Winslet are in top form(especially Carrey, who should've won a friggin' Oscar) Joel and Clementine, two very different people who have seen their once loving relationship turn to dust. Overcome with grief, Joel undergoes a dicey procedure to have his memories of her completely erased. However in the midst of it he comes to a realization, stirring not just in a brain but deep in his soul, that to forget this woman who has been such a huge part of his life would change him profoundly.
Charlie Kauffman and director Michel Gondry cooked up the story, I'm assuming while they were high on peyote and watching old tired romance movies. Whatever it was that sparked it, what they came up with as a masterpiece and one of the truest movies about love you'll ever see. I dare you not to cry during the "Meet me in Montauk" scene.