In Chapter 5 of Fitzgerald's The Great Gatsby, what problem does Gatsby begin to have as his secretive meetings with Daisy continue?

Gatsby begins to have a problem with Daisy as his dream of recapturing her is effectively over and he must now work to sustain her interest in him.
For years Jay Gatsby has worked and planned for the attainment of his "grail," Daisy Buchanan. So nervous and excited is he on the day of their meeting at Nick's cottage that he runs out into the rain and walks around Nick's house. When he re-enters, he is wet and awkward, knocking over Nick's clock on the mantel, a symbolic gesture that signifies the end of time.
Having rekindled the love of Daisy and impressed her with his wealth and splendid possession--such as his gold bathroom fixtures and his custom-made English shirts, which bring tears to her eyes as she buries her head in them--Gatsby must now try to maintain Daisy's interest and desire for him. For, it is obvious that the quantitative value of money is what rules Daisy's desires, as evinced by her change of heart in marrying Tom after he sent her a $350,000 pearl necklace.
Indeed, it is "the colossal vitality of his illusion" (Ch.5) that Jay Gatsby must maintain in order to keep his hold on Daisy. He may love her, but Daisy's passion is ignited by the charm of money and social ambition.