a good example of the characteristics of a medieval romance. First, it features King Arthur and the knights of the round table. King Arthur and his knights followed a code of chivalry, which included having honor, bravery, loyalty, and gentlemanly manners. It also included committing acts of selflessness for the benefit of others.

Sir Gawain and the Green Knight fits the characteristics of a heroic knight as the protagonist in a medieval romance. Gawain is challenged by a mysterious green knight to cut his head off with a splendid looking ax. He does this with the understanding that the green knight will return in one year and one day to do the same to Gawain. Gawain beheads the knight in one stroke, showing bravery and courage. Supernaturally, the green knight does not die, and he picks up his head and promises to return.  

Later, Gawain sets off on a quest to find the green chapel so that he can fulfill his side of the bargain. This shows his honor, as he is keeping his word even unto death. It also shows his bravery by allowing the green knight to behead him. These are two characteristics of a medieval romance.

On his journey, he meets  Bertilak de Hautdesert, the owner of a beautiful castle, and his wife. Lady Bertilak tries to seduce Gawain, but he refuses her advances and acts honorably toward her, being careful not to offend her, thus displaying a chivalrous attitude. 

When Gawain meets the green knight, he submits to the beheading, but the green knight only causes a scratch on his neck. Then he reveals that he is really Bertilak and has been transformed by magic. This is another characteristic of a medieval romance—supernatural elements. Bertilak tells Gawain that the whole thing was a trick, set up by the sorceress Morgan Le Fay, to test King Arthur's knights. Gawain is afraid he failed the test, but Bertilak assures him that he conducted himself admirably.

A medieval romance is a literary genre that developed in the Middle Ages, albeit closely following such antecedents as the ancient epic and the late antique novel (such as the works of Apuleius and Longus). Romances can be written in prose or verse, with the prose ones tending more towards fictionalized history and the verse ones towards pure fiction. They tell the stories of aristocrats engaged in feuds, love relationships, and quests. The romances draw their materials from a range of historical or quasi-historical sources, including the courts of Charlemagne and King Arthur and traditional stories such as those of Tristan. Supernatural and fantastic settings and events are common.

Sir Gawain and the Green Knight is typical of the genre in many ways. It was written during the medieval period. The protagonist is a knight in the Arthurian court. He embarks on a quest. The quest has many supernatural and fantastic elements. It has a theme of chivalry and the appropriate forms of ethics and courtesy expected of a knight. It includes elements of both the masculine heroic journey and romance in the sense of relationships between men and women.

Medieval Romances typically exhibit the following characteristics:

-Arthurian tales which deal with the quests and challenges of Arthur and his knights.

-Tells a story of a single knight and a single quest.

-The story exists within the constraints similar to a fairy-tale.

-The story contains elements of courtly love- Courtly love is the relationship between a knight and his lord's lady. The knight is required to love and respect the lady within the same way which he loves and respects his lord. The love the knight holds for the lady is fueled by his desire to please her and, therefore, to be worthy of her love and/or to win her favor.

-Typically, the knight must face the challenge of maintaining a balance between chivalry and love.

Based upon these characteristics, Sir Gawain and the Green Knight contains many of the elements to be considered a Medieval Romance.

First, the story deals with one knight, Sir Gawain, and a single quest. Gawain promises to meet the Green Knight one year from their initial meeting to receive a blow from the Green Knight in exchange for the one Gawain gave to him.

Second, the story contains elements which includes fairy-tale like aspects. The Green Knight is mystical. The fact that he was able to lose his head and stay alive alludes to a supernatural element seen in typical fairy-tales.

Third, the story contains elements of courtly love. Gawain must show both Lady Bertalik and Guinevere courtly love. As charged by his position as a knight to Arthur, Gawain must show Guinevere love and respect. In the same way, given Gawain is sheltered at Bertalik's, he must show Lady Bertalik the same kind of respect and love.

Lastly, Gawain greatest challenge is finding a balance between chilvarly and romantic love for Lady Bertalik.

Medieval romances are rooted in the tradition of Greek romances:

The stories, often about faithful lovers separated and reunited after perilous adventures, were carried on in the oral tradition. 

Sir Gawain and the Green Knight is written in a style similar to the stories of King Arthur and the Knights of the Round Table.

The early chronicle accounts of Arthur all contain the elements of love, mystery, adventure, and psychology that have now come to be associated with romance. 

These stories often dealt with chivalry (the most important piece of this tale), which is:

Heroic warfare [which included] chivalry: standards of conduct especially when dealing [with] someone on your same level.

Chivalry is also defined as,

The sum of the ideal qualifications of a knight, including courtesy, generosity, valor, and dexterity in arms.

They also can address themes of courtly love, bravery, a knight's prowess in battle, a dedication to the Virgin Mary, and psychology, as well as including the presence of the supernatural (things beyond the natural realm). While other stories (such as the epic tale Beowulf) generally have tragic endings, medieval romances often have favorable ones.

This story begins at Christmastide, when the mysterious Green Knight appears at Arthur's court and issues a challenge to anyone who will take it: a swing for a swing. The man who accepts his contest will have first swing at the Green Knight. Young Gawain, in a show of bravery, accepts the terms and cuts the Green Knight's head off—whereupon the Green Knight picks up his head, which (resting in the Green Knight's hands) demands that he have his opportunity with Gawain, a year from that day. This introduces the element of the supernatural.

A year later, Gawain travels to meet the Green Knight as agreed—his chivalric code demands that he keep his word. On his way he comes upon a castle where he is welcomed by Lord and Lady Bertilak. While the lord hunts each day, his lady tries to seduce Gawain, who gallantly resists. However, on the third day she gives him a belt ("girdle") that will protect him from harm. Although his code demands that he return it, fear for his life makes him keep the gift.

Valiantly, Gawain goes out on the appointed day to meet the Green Knight demanding they begin what was started a year before. With the first swing, the Knight stops himself. However, when the Green Knight positions himself for a second swing, for all Gawain's bravery and even the possession of the magical green belt, the younger man flinches at the swing, betraying his chivalric code. The Green Knight chastises Gawain and questions his reputation as a valiant knight.

Gawain pulls himself together. He promises not to move and declares:

And this much is plain:

My head, if it falls, won't talk in my hands (2282-2283).

Once more the Green Knight stands to take another swing. Rather than cutting off the young knight's head, the Knight simply nicks his neck, whereupon Gawain rises to defend himself. It is at this time that the Green Knight reveals his identity: he is Lord Bertilak. He explains that his wife's behavior was a test for Gawain. Gawain broke his code first in taking the belt and, later, in flinching. The Knight explains that Gawain "failed a little/lost good faith. . . for the love of your life" (2366, 2368).

Gawain is distraught and devastated:

Fear of your blow taught me cowardice,

Brought me to greed, took me from myself

And the goodness, the faith, that belong to knighthood.

I'm false, now, forever afraid

Of bad faith and treachery (2379-2383).

Gawain begs the Knight to forgive him and promises to try "to sin less" (2388). The Green Knight immediately does so.

While the story ends happily enough (Gawain does not die), the reader gets the sense that Gawain will never see himself in the same light. Herein lies the element of psychology—he has learned a valuable lesson that will drive him to live a more chivalric life from that point on; his failure to follow the code that guides his actions is a blow from which he will not quickly recover but will motivate him to lead a more chivalrous life.

Additional Sources:

http://online.hillsdale.edu/file/great-books-101/week-11/Week-11---Jackson-GB-101-2014-Readings.pdf

Adventures in English Literature, Harcourt Brace Jovanovich Publishers: Orlando, 1985.

Critics identify several characteristics of a medieval romance, and Sir Gawain and the Green Knight fulfills these characteristics in several ways.  I would like to focus on the following main characteristics:

1. Medieval romance usually idealizes chivalry

The concept of chivalry relates to the behavior of knights and their treatment of women. Knights were expected to show the highest level of respect for women including maintaining their chastity and showing a reverence toward them indicated of the Christian love for the Virgin Mary.  They would should this reverence by dedicating their battles to a particular lady, perhaps representing her family colors in doing so. Gawain shows this for the Lady of the castle in that he denies her sexual advances without hurting her feelings, refuses her expensive gifts which he cannot repay and accepts her green scarf as he rides into battle.

2. Medieval romance idealizes the hero-knight and his noble deeds.

The hero-knight is expected to show unparalleled loyalty for his king, honesty in all areas and bravery at the face of death.  Gawain exhibits all three.  First, he accepts the challenge of the Green Knight when nobody else will except for Arthur himself.  This challenge involves basically traveling to the Green Knight's home to receive a blow to the neck - certain death.  While at the Lord's home, he does not lie about his kisses with the wife, but instead returns them as promised to the Lord.  Even when presented with a plan avoid certain death, he keeps his promise of meeting the Green Knight.  Finally, he accepts not one, but three blows to fulfill his obligation to the Green Knight.

Ultimately, Gawain shows his level of nobility by his level of self-hatred upon what he perceives as failure.  He keeps the sash for personal reasons and does not give it to the Lord.  This shows his fear for his own safety.  Even though King Arthur, the knights and the Lord all forgive him for this, he still sees himself as a failure.  In a way, this is how the work shows its comment upon how the level of behavior that knights are expected to uphold may be unrealistic.