There's a moment of almost painful awkwardness when she pulls away. Part of him wants to do something at least vaguely comforting, but he knows that wouldn't go over well. So he figures the best thing to do is to give her some space so she can keep her dignity or something. "I uh, I gotta take a piss before we go."

He let's her have some privacy while he deals with the consequences of downing a few beers.