Eleonora becomes very sick, and she told The Narrator that shes not afraid of dying; but of him leaving and loving someone else. So he vows to her and to heaven that he will never leave her or love anyone else.
Eleonora promises to watch over The Narrator and show him her presence after she dies. Then she dies and keeps her promise.
The Narrator stays in the valley for some time, but then it starts to die slowly. So he moves to a big city and Eleonora stops showing up.