The lord of the castle proposes a deal to Gawain. According to the agreement, the host leaves with his men to hunt until evening. Gawain, meanwhile, stays in the court. At the end of each day, the lord is supposed to exchange everything he acquired during the hunt for everything the guest got while staying in the castle.
In his attempts to find the Green Knight, Gawain comes across Hautdesert castle. There he meets the owner whose name the reader finds out only at the end of Sir Gawain and the Green Knight. The owner and Gawain make a deal to which the main character happily agrees. As it is found out later in the story, this agreement is just another instrument for completing Morgan le Faye’s plan. Through making this deal, Gawain inevitably put himself in a position where he would have to choose between honesty and his life.
The lord’s wife had a green girdle with magic properties that had the ability to protect its wearer from death. Gawain knows that this would be his only chance to survive a blow from the Green Knight. Hence, he lies to the host and does not give him the girdle. Obviously, this is a moment of the main hero’s weakness. Yet, he manages to turn this dishonoring situation into an honorable one later. Gawain keeps wearing the girdle on his arm as a reminder of his liability to himself and others.