Was diasy's final choice a surprise when Gatsby confronts Tom, and does her character support her actions?
Tom knows that Daisy's innate snobbery is ultimately identical with his own, therefore he uses it to his own advantage. She would never desert her aristocratic husband for "a common bootlegger," regardless of the love she felt for the bootlegger in question. Daisy refuses to submit to Gatsby's pleas, and will not say that she has never loved Tom. Gatsby is ultimately unable to recapture his idyllic past; the past, the future, and Daisy herself ultimately belong to Tom.
The distinction between "old" and "new" money is crucial in this chapter. While Gatsby earned his fortune, Daisy is an aristocrat, a woman for whom wealth and privilege were available at birth. As Gatsby himself remarks, even her voice is "full of money." This is what he loves in Daisy's voice, and in Daisy herself: for Gatsby, Daisy represents the wealth and elegance for which he has yearned all his life. Gatsby thus loses Daisy for the same reason that he adores her: her patrician arrogance.
This decision is completely in tune with her character. She is a spoiled rich girl, who has always allowed others to make decisions for her. She will not give up her name or social status. She's foolish, but she's not stupid. Daisy understands that to have chosen Gatsby would have meant giving up her name, status, and let's not forget, her child.
http://www.gradesaver.com/the-great-gatsby/study-guide/section7/
