Maupassant's "A Coward" tells the story of a man (Viscount Gontran-Joseph de Signoles) who challenges another (Georges Lamil) to a duel, becomes anxious and afraid in the days leading up to the duel, and finally kills himself with his gun rather than face the ignominy of possibly fainting at the duel.

The main theme of the story is the theme of social expectations, and specifically the expectations that society (in this case a nineteenth-century society) has of men. In the story the Viscount is acutely aware that, as a man, he is expected to be chivalrous, honorable, and brave. Accordingly, when he sees that one of the ladies he has invited out for ices is becoming upset because another man is staring at her, he promptly does what he thinks he is supposed to do, and, in the name of chivalry, challenges the man to a duel. Having done this, he reflects, and decides that:

He had done what he was compelled to do; he had shown himself to be what he ought to be. People would talk of it, would approve of him, congratulate him.

The key words and phrases in this quotation are "compelled," "what he ought to be" and "People . . . would approve." The Viscount's decision to act chivalrously and challenge the other man to a duel, is clearly not borne out of anything other than the pressure to live up to social standards of masculinity.

After this moment it becomes clear that the Viscount is nervous, and increasingly afraid of the duel ahead. He drinks "three glasses of water one after the other," and hopes that his adversary will "retire and apologize." He then starts to imagine what might happen at the duel, if his fear continues to escalate, and his first thoughts are not for his own self-preservation, but for the social embarrassment that he will inevitably suffer if he faints. He thinks of:

the disgrace, of the whispers at the club, of the laughter in drawing-rooms, of the contempt of women, of the allusions in the papers, of the insults which cowards would fling at him.

The Viscount's decision to challenge Lamil to a duel, his fear of possible social embarrassment, and also his decision at the end of the story to commit suicide rather than risk social embarrassment, all point to the fact that the expectations he was expected to live up to, as a man, were both irrational and debilitating. Those expectations started a domino effect, beginning with a woman who took offense at the way a man was looking at her, and ending with another man thrusting the barrel of his pistol into his mouth, and pulling the trigger.

Guy de Maupassant's short story "A Coward" deals first and foremost with the theme of egocentricity vs reality.

The main character, Vicomte Gontran-Joseph de Signoles, is a foundling who came upon great fortune once he is  adopted by a powerful family. As an adult, the young Vicomte becomes the epitome of the French dandy: Good looking, well-spoken, charming, seemingly virile, and quite admired. He is so admired that his nickname is "Handsome Signole" among his cronies.

As it is to be expected, all this validation of his beauty and charms has gone straight to the Vicomte's head. Now, with the support of so many admirers, the Vicomte has come up with his own version of himself: In his world, he is the best guy on earth; a version of a musketeer. He has been put on a mission, he believes, to become the ultimate charmer.

However,  Handsome Signole's ego becomes so big that he begins to believe in every attribute everyone has ever given him. He is sure that he could take anyone in a duel and win. In fact, he was hoping for the opportunity.

One night, his opportunity materialized: Signole scolded a man who was staring and one of Signole's female friends during a night soiree. The man warns Signole to leave him alone. Signole refuses, and slaps the man in the face. As a result, Signole demands that a duel should occur to satisfy the honor of the lady and his own dignity as a man who has been insulted.

Yet, reality sinks in. It is not the same thing to plan something as it is to do something. When Signole, for the first time, had to retrieve strength from the REAL man he is, he realizes that there is no strength to be found. He is scared. He is a coward. He has lived too long under a fantasy that he is this or that...but he is far from it.

In the end, he shoots himself in a panic, not knowing what would come out of the duel. If he loses, his ego would have been hurt forever (not to mention that he will likely be dead). And the chances for winning? Not very many, from what he can confess to himself.

Therefore. There is the coward: The man whose self-love and egotism blinded him to the fact that he has weaknesses too, that he is a regular man, and that he also can die, be scared, and back out of things. Egocentricity vs. Reality: That is the central theme of the story.