While Gawain stayed at the lord's castle, they had a little bargain. For the next three days, whatever the lord gain from the hunt will be given to Gawain. However, whatever Gawain receive in the castle will be given to the lord. Gawain received a deer on the first, a boar on the second, and a fox from the lord on the third day.
Good day for a hunt
While Gawain stayed in the castle, the lord's wife went to his room and they talked. The wife gave him one kiss on the first and two kiss on the second and Gawain kissed the lord as well. But on the third day, the wife gave him a magic girdle that would protect him from any harm. Gawain did not upheld the bargain and he kept the girdle.
Thank you and I shall accept.
This girdle will protect you from any harm.
After his stay with the lord, Gawain sets of to find the green chapel. He wore the girdle given to him by the lord's wife. To his dismay, he was shocked how the chapel looked.
What is this! This is no chapel, this is the entrance to hell itself!
After confronting the green knight, flinching, and getting a scrape on the neck, the green knight revealed himself to be the lord earlier. He was not please at Gawain for breaking their bargain.
Our deal was you are to give me whatever you received. Not only did you not give me my girdle, you kissed my wife and I should kill you for that.
Gawain apologies for his action calling himself a coward. The lord forgives him and gives him the girdle as a remembrance.
I'm truly sorry for my action, Here is your girdle.
I forgive you. Also, keep the girdle as a sign of this meet.