The Once and Future King Book 3, Chapter 39
Lancelot performs perfectly at the tournament. He cannot tell Elaine he doesn't want to stay with her. She is sensitive enough to try to pretend she hasn't been hurt all these years, and she tries not to expect much from him. This moves him, so that he feels obligated to do what she wants. When he wears a cloth she made at the tournament, Guenever finds out and is furiously jealous. But Lancelot finally seems about to tell Elaine he will leave her again.