What symbolic purpose does Ellen Halloway, her choices, and her fate serve?

The final sentence in Wacousta focusses not on the happy lovers but
on Ellen Halloway’s disappearance. Margaret E. Turner calls her “the ghost in Wacousta” (187), and Manina Jones argues that she“haunts” the novel: certainly her curse drives this novel and its sequel. What symbolic purpose does Ellen Halloway, her choices, and her fate serve?