Alleged Affair with Queen Guinevere stop Sir Lancelot
There was report of a fight between Sir Galahad and Sir Lancelot over Lancelot's rumoured affair with Queen Guinevere. The fight was allegedly fierce and Sir Galahad surprisingly knocked Lancelot off his horse.
Recently, Lancelot sent a message to Camelot from Castle Corbenic. In the message, he admits being denied entrance to the castle containing the Grail because of his strong love for maidens. Lancelot is known for involvement with women and it is not surprising that his lack of purity of heart and mind had prevented him from entering the Grail castle.