The Gift of the Magi
The narrator doesn't guide either of the protagonists – they don't even know he exists – and he doesn't factor into the plot, so he's not a traditional guide in that sense. But the narrator is a guide for someone else: us, the audience. He's trying to teach us a lesson, and he uses the story of Jim and Della to do so. Though he doesn't guide Jim and Della, it is the narrator who reveals meaning behind Jim and Della's action and tells us that they're good actions.