"Sir Galahad shown Guinevere to be a whore"

Sir Galahad is a knight of the Round Table in Arthurian legend.  He is renowned for his virtue and particularly his chastity, which gained him the name Sir Galahad the Pure.  Guinevere, by contrast, is a character notorious for her unchastity: married to King Arthur, she was the lover of Lancelot.  In some versions of the Arthurian stories, Galahad and Guinevere have a particularly close and warm relationship before her adultery is exposed.