Why did Emily kill Homer Barron in "A Rose for Emily"?

Although author William Faulkner never specifically tells
us that Emily was responsible for Homer's death, we can certainly assume that she did
so. Why she killed him is more complex. Although most of the townspeople assumed that
the two would eventually marry (Emily purchased wedding-specific items beforehand),
Homer must have told her that he was going to maintain his bachelorhood; or, perhaps,
Emily realized that the marriage was never going to happen. She did not want to give him
up; so, much in the way that she did not want to allow her own father's decaying body to
be removed from the house after his death, Emily must have figured that keeping Homer
with her (even as a corpse) was better than being alone without him. There may have been
an argument that resulted in the murder, or, more likely, Emily poisoned him while he
slept.