What are the events that forshadow the ending?

When Emily's father dies and she keeps his body for a time without admitting he is dead, we know she does not want the men in her life to desert her, so Homer's death is predictable. The smell after she buys the "rat poison" indicates that she has killed "something" which fits that it happens just when Homer "disappears." The fact that Homer "liked the boys" hints that any interest he has in Emily is not just for her, and thus, she would have to force him to stay with her.