First of all, there is the issue of Homer Barron's ancestry. He is a northerner, living in a Southern region that was still smarting from its loss in the Civil War. The Yankee also worked with and was obviously friendly with his crew of black laborers. He also stood to profit from construction in the south, another fact that would have caused great consternation among the townspeople.

In addition, the townsfolk, especially the older ones, whispered about how Miss Emily was violating the principle of noblesse oblige. In exchange for the social prestige that the town had accorded her, the townspeople expected a certain amount of social responsibility from their Miss Emily.

This includes being aware of her class and social background. It certainly did not bode well for Miss Emily, and by extension the town, that Emily was cavorting with a Northerner who was also a day laborer. Miss Emily had committed a cardinal sin of taking up with a social inferior.

Homer Barron announced his decision to leave Yoknapatawpha County to return north. Miss Emily purchases arsenic, and due to gender expectations and her social standing, the townspeople can only assume that she plans to commit suicide. Later, as a foul stench emanates from her home, even the judge could not bring himself to tell a lady that her home "smells."
The townspeople's views and social mores therefore had a very strong influence on the life of Miss Emily. Social views regarding the proper role of women caused Miss Emily to chafe under the rule of a traditionalist father. The townspeople's disapproval of her affair with a northerner/day laborer further wrecked any chance she had at happiness. In the end, she could only live as a prisoner in her own home.

A Rose for Emily - Symbolism of Social Conflicts in the New South