In the conclusion of Ethan Frome, the narrator entered Ethan's house as a courtesy from Ethan considering that he had been the man's driver for a while. He had known the story of Ethan as the reader learned about his love fantasy with Mattie, how they plotted a sudden suicide pact, and how the pact failed, leaving Ethan into a near-paralyzed man.
We know that, as the narrator approached he heard what he described as a "querulous drone", or a voice nagging and complaining almost incessantly. We discover that the woman who is nagging is none other than Mattie herself, who has become now an invalid due to the accident, and a bitter one at that. To add to the pain, Zeena is ultimately both Mattie and Ethan's care taker, making the oppression of Ethan and Mattie not only physical but moral, psychological and fateful.