LitCharts assigns a color and icon to each theme in The Once and Future King, which you can use to track the themes throughout the work.
Chivalry, Satire & Medieval Life
Fate (Time)
Quest and The Holy Grail
Might vs. Right
War
Summary
Analysis
The days and weeks of waiting for Lancelot to come back to Guenever turn into months. Guenever grows angrier, angry at Lancelot's selfishness, for abandoning her soul to save his own. Lancelot sees these things too, but cannot give up his newfound purity.
White describes—as Guenever sees it—a certain selfishness to Lancelot's piety. His piety comes at the cost of Guenever's happiness—in this manner it seems immoral that piety can sacrifice another's well-being.
Active
Themes
This all comes to a head one morning while they are singing alone together. Mid-song, Guenever closes the music books. She asks Lancelot to leave again; she does not want to quarrel or make a scene, but he is wearing her out and it would be easier if he were not there. Lancelot stands up and walks to the window. Suddenly he speaks in a harsh voice: "If you like, we will start again." He swings round to find the room empty. He packs his scanty belongings and sets off from Camelot the following morning.
This scene exposes the fragility of Lancelot's religiosity: with only gentle convincing, he is willing to give up his months of trial to be with Guenever again.