Two precognitives meet and fall in love. Their relationship is fraught by the fact that one of the precognitives is a determinist (seeing the future as a single stream) and the other believes in free will (and sees possibilities branching from most moments). The philosophical contrast and science fictional premise provide an intriguing philosophical flavor to the human romance; the two work exquisitely in synchrony.
She said it better and far more concisely than I was going to manage (clearly), but you all must read this story. I wanted a little bit more from the ending, but that's only because I wasn't ready for the story to end. Charlie Jane Anders did what she needed to with the story, but I was hooked and wanted more.
If you want a preview of my Hugo ballot, know that it is rather likely to include this story.