How does Gatsby's facade start to fade when he comes over for tea?

Gatsby's facade starts to crack when he comes over to Nick's for tea because he is so unspeakably nervous about seeing Daisy again. He has sent someone to mow Nick's lawn and deliver inappropriately large amounts of flowers.  He is so anxious to be impressive. He clearly tries to adopt what ends up being "a strained counterfeit of perfect ease," and he almost knocks Nick's clock onto the floor with his head before he barely catches it with shaking fingers.

Further, Gatsby is trying so hard to be cool, but he knows precisely how many years it's been, to the month, since he last saw Daisy—a very uncool thing to blurt out in front of the woman he loves. When Nick tries to leave to give them a bit of privacy, Gatsby barks rudely at him, "Where are you going?" and he follows Nick out, leaving Daisy alone. Then, he is so embarrassed that all he can do is complain about what a bad mistake arranging this meeting was. His too cool, "old sport" routine fails him here.