Pelleas and Ettarre

Pelleas falls in love with Ettarre, who asks him to win a golden circlet for her at a joust.  Pelleas wins the tournament, at which point Ettarre accepts the prize and begins to become annoyed by the presence of Pelleas, who, despite her cruelty to him, remains faithful "like a dog before his master's door."  Ettarre sends him away, and meeting Gawain, Pelleas accepts that knight's offer to cause Ettarre to regret her actions by telling her that Pelleas has been killed and was the best and bravest knight.  After Gawain fails to return after three days, Pelleas visits Ettarre's abode to find Gawain in bed with Ettarre.  Deciding not to kill them both, Pelleas places his sword across their throats and leaves.  The affair causes Ettarre to love Pelleas though too late. 

On the way to Camelot, Pelleas meets Percival, who tells him about the affair between Lancelot and Guinevere, though refusing to malign the Queen.  Pelleas later meets Lancelot and the two battle, with Lancelot proving himself stronger.  They ride back to face the Queen, who realizes that Pelleas knows her secret shame.  Modred knows the secret will soon become known to Arthur, saying "The time is hard at hand."

All of the knights seem to know the sin of Lancelot and Guinevere.  Pelleas, newly knighted, at first upholds Guinevere as the ideal model for a wife:

                                                  'Where?

O where? I love thee, though I know thee not.

For fair thou art and pure as Guinevere,

And I will make thee with my spear and sword

As famous--O my Queen, my Guinevere,

For I will be thine Arthur when we meet.'

Using Guinevere as the ideal wife, however, causes him to be ensnared by the beauty of Ettarre, who uses him and never loves him.  He realizes "I never loved her, I but lusted for her."  Ettarre is similar to Guinevere in that the Queen never loved Arthur.  Pelleas, much like Arthur, remains faithful but is rejected by Ettarre.  Instead, he finds Ettarre sleeping with a fellow knight whom he trusted.  The episode, along with Percival's revelation of the affair, changes Pelleas' perception of the Queen; she is no longer his ideal.  When he stands before her at the end of the ideal, she realizes that he too knows of her sin with Lancelot:

                                          'O young knight,

Hath the great heart of knighthood in thee failed

So far thou canst not bide, unfrowardly,

A fall from him?' Then, for he answered not,

'Or hast thou other griefs? If I, the Queen,

May help them, loose thy tongue, and let me know.'

But Pelleas lifted up an eye so fierce

She quailed; and he, hissing 'I have no sword,'

Sprang from the door into the dark. The Queen

Looked hard upon her lover, he on her;

And each foresaw the dolorous day to be.

Guinevere, no longer viewed as a model wife, is hissed at and snakebitten by his response and by the thought that Arthur will soon find out the secret.  She sees she is no longer respected as Queen, the affair having lower her in the estimation of the knights.