Nick is out of the living room in his house during the first few minutes that Gatsby and Daisy discover each other's presence at Nick's house that afternoon. When he joins them, he finds them very awkwardly trying to be correct and polite when both are actually quite uncomfortable and embarrassed in each other's company.
Nick creates an excuse to leave the living room and then the house for a long enough period of time for Daisy and Gatsby to move past the initial shock of rediscovering each other. When Nick returns to the living room, Daisy's face shows that she has been crying. Gatsby, however, is radiant. During Nick's absence, Gatsby and Daisy have acknowledged their longing for each other during the years of separation. For Daisy, this is made bittersweet by her marriage to Tom; for Gatsby, this is the realization of his every fantasy and dream.