How are Daisy and Gatsby different when Nick returns to the house after a half an hour?
When Nick exits his cottage it's raining. He leaves Daisy and Gatsby there in an awkward state of embarrassment, the result of not having seen each other for five years. When Nick returns the sun has come out, both in terms of the weather and the couple. He notes that "every vestige of embarrassment was gone" from the twosome. Daisy had been crying, but jumps up to wipe her tears away in front of a mirror when Nick enters the room. Gatsby, however, has undergone the biggest change. He had been nervous and uncertain earlier, yet now he "literally glowed ... a new well-being radiated from him and filled the room." Daisy's voice, says Nick, sounded full of "unexpected joy."
Gatsby wants to show Daisy his house, so he, Nick and Daisy go next door. As they tour the house, Nick realizes that Gatsby has already been through two stages--embarrassment and "unreasoning joy"--and now has entered a third, "consumed with wonder" that Daisy is there. The absolute high point of his delight has passed and, while still very happy, he is "running down like an overwound clock."
When Nick left, Gatsby was full of nervous energy. When Nick returned, Gatsby seemed a bit puzzled and in his own world. Nick realized that Daisy did not meet his fantasy expectations, yet Gatsby was too far into his make-believe image of Daisy for him to give up on his dream.
When Nick returns after giving Gatsby and Daisy 30 minutes to themselves, Daisy's face is tear-stained and Gatsby is glowing. It is clear that the two of them have shared some deep emotions and that Gatsby, at least on one level, believes his dream is slowly becoming reality.