In Ethan Frome, Wharton uses a frame story to bookend the main narrative. The novel's Prologue and Epilogue are both told from the perspective of the Narrator, an engineer who comes to Starkfield and becomes fascinated with Ethan, about whom he knows very little. The rest of the story takes place more than 20 years earlier. It's told using third-person perspective and grants the reader insight into Ethan's thoughts.
Wharton's use of a frame story accomplishes three main goals: first, it builds tension and suspense. The audience knows from the beginning of the story that Ethan was involved in an accident, but they must spend the novel waiting to find out the details. Second, the frame story creates a sense of inevitability, which emphasizes the theme of determinism and free will. Wharton often implies that Ethan's fate is the result of his inability to take an active role in his life, but the novel's narrative form dooms him. No matter what choices he makes, his story will ultimately end in tragedy, or else the frame story would be different.
The frame story also creates a sense of distance between the reader and the novel's characters. Because the frame story is told in first person, the reader is encouraged to identify with the Narrator, who is an outsider in the town of Starkfield. The reader is separated from Ethan's story by over two decades, and they do not get any glimpses into his current state of mind, relying only on the Narrator's impressions of him. Although Wharton's use of a frame story is reminiscent of Romantic and Gothic novels like Wuthering Heights, this narrative distance is consistent with the influence of Naturalism on the novel, as other works of Naturalist literature often featured a similarly detached tone.