The Once and Future King Book 3, Chapter 22
Lancelot tells Elaine that he will stay with her if that is what she wants, but he will not marry her, because marriage implies love, and he would only be doing it out of obligation. Elaine says she would be very happy living with him. They move into Bliant Castle, and Lancelot calls himself the Chevalier Mal Fet, so no one will know who he is. He is very uncomfortable living there with Elaine, but he feels obliged to stay.