"A Rose for Emily" takes place shortly after the Civil War when the south was undergoing a major upheaval, both culturally and physically. The elegance and gentility that once defined the old south slowly faded into the past. Emily, herself, goes through a dramatic change of character.
"Emily is born to a proud, aristocratic family sometime during the Civil War; her life in many ways reflects the disintegration of the Old South during the Reconstruction and the early twentieth century. Although her mother is never mentioned, her father plays an important part in shaping her character. He chases away Emily’s potential suitors because none of them are ‘‘good enough’’ for his daughter."
Emily turns into an eccentric, outdated, recluse, fighting the change that is inevitable, even resorting to murder.
Emily is in a transition period in history, so her character experiences the sensation of not belonging. She holds onto the illusion that the past is still alive, therefore distorting her perception of reality.
"Faulkner based part of the character of Emily on a cousin, Mary Louise Neilson, who had married a Yankee street paver named Jack Barron. More importantly, the character of Miss Emily is the town eccentric—Faulkner certainly understood eccentricity, having made it a lifelong practice."
Faulkner's "A Rose for Emily" has many themes, among them, the ones you mentioned. Explaining them can be done through Miss Emily's resistance to change, to begin with.
Miss Emily was living in the past. She and her home were relics in the town. While the town as progressing and growing around her, Miss Emily and her home were stagnant and dilapidated. She was so out of touch with reality that she was unaware of many things going on outside of her own home. She truly did live in what seemed like an illusion, a far-gone time.
Miss Emily certainly would have liked to have had time stand still, but we all know that cannot be. Miss Emily wasn't willing to change with the times, and this contributed to her demise. If one cannot accept change, one becomes stagnant and quite frequently, cannot function effectively in society.
As far as death and life, Miss Emily tried to keep love by killing Homer; in death, she thought she could preserve love. In the end, she took a human life and still died lonely and ultimately, surely never being able to experience real love.
For more help with this, see the discussion of themes in Rose for Emily.