The Great Gatsby Reading Notes: Chap. 8

In chapter 8 it gets very interesting, I almost didn't want to put the book down. As the story continues Nick tries to convince Gatsby to forget about Daisy but he refused and ignored his decision. After a long period time Gatsby and Daisy make love with one another and they were going to get married once Gatsby came back from the war, but then Daisy decides to marry Tom, *which by the I thought was really messed up, just saying*. But after all the things that Gatsby and Daisy shared and did together, why did Daisy choose Tom? Why did Daisy break her promise to Gatsby? What was her reason for leaving him?