What does Fitzgerald try to emphasize at the end of chapter 7?
As chapter seven closes, the reader recognizes a series of ends. Myrtle Wilson's life has violently ended, and with it, her dream of escaping the Valley of Ashes. With Daisy back in the Buchanans' home, deep in conversation with Tom, it seems her relationship with Gatsby will end. Nick's disgust with Jordan's callousness in the wake of Myrtle's death suggests that their relationship is winding down. Nick notes that it is September, the end of the summer. And Nick's final observation of Gatsby at chapter's end is that he stood outside Daisy's house, "watching over nothing." If we look back to chapter one where Nick tells us that he returned to the Midwest from the East in the autumn, we realize that Nick's time in New York is also coming to the end.
Fitzgerald, F. Scott. The Great Gatsby. Charles Scribner's Sons, 1925.