Arrowsmith by Sinclair Lewis

With Terry Wickett gone, Martin returned to phage. He made a false start and did the worst work of his life. He had lost his fierce serenity. He was too conscious of the ordeal of a professional social life, and he could never understand that esoteric phenomenon, the dinner-party-the painful entertainment of people whom one neither likes nor finds interesting.

So long as he had had a refuge in talking to Terry, he had not been too irritated by well-dressed nonentities, and for a time he had enjoyed the dramatic game of making Nice People accept him. Now he was disturbed by reason.