what does the beginning of the novel suggest about the reliability of the information presented in the story?

The frame story (introduction and conclusion) is told in the first person, from the narrator’s limited point of view as a visitor unfamiliar with Starkfield and Ethan Frome. However, most of the book is written in the third person limited, in which the narrator accesses Ethan’s thoughts but not those of the other characters. The narrator himself is rather nondescript. He seems reliable but certainly not completely all knowing as an omniscient author might be.

Source-link for part of the above.