Marriage is the true antagonist in the story. Mrs. Mallard has no real issue with Mr. Mallard. He was not an abusive or unkind husband, and she does have feelings of sadness that he is dead (as she believes). She recalls that she even loved him sometimes.

What she objects to, and is thrilled to be liberated from, is the assumption that she must constantly, in many subtle ways, conform her life to her husband's. She has had to constantly think of his needs. He has not been cruel to her, but the set-up of the society they live in has nevertheless stifled her.

As she begins to realize what has happened, the joyous word "free" comes to her. She thinks:

There would be no one to live for during those coming years; she would live for herself. There would be no powerful will bending hers in that blind persistence with which men and women believe they have a right to impose a private will upon a fellow-creature.

It is not Mr. Mallard as an individual who she objects to but the institution of marriage. One is tempted to think it is patriarchy which is the antagonist, and that too is implied, but what Mrs. Mallard is truly thinking of is the stifling confines of marriage as it was practiced in her time--she speaks not only of men, but of the "blind persistence with which men and women believe they have a right to impose a private will."

Mrs. Mallard simply wants to be free to be herself. Her conflict is that her society does not condone that path.

The conflict in Choplin's classic short story can be considered a Woman vs. Society conflict, where Louise Mallard struggles to overcome the oppressive aspects of a patriarchal society, which prevents her from exercising personal agency or embracing independence. Choplin's story is set in the late 19th century, which was a time when women had little to no rights and society expected them to remain docile and obedient to their husband's will. Mrs. Mallard was expected to remain indoors, carry out her husband's wishes, and perform necessary domestic duties. Although Louise Mallard loves her husband, she resents the submissive, oppressive nature of her restricted marriage. Louise Mallard desires to experience autonomy and live completely for herself, which is something that institutional marriage and society prevented at the time. Therefore, Louise Mallard's conflict is with society's expectations of married women and her struggle to experience independence in a male-dominated society.

The main conflict in "The Story of an Hour" is character vs. society.  Mrs. Mallard's adversary is not her husband, as some might argue, but society, due to society's expectations for right female behavior as well as marriage.

First, Brently Mallard was a good husband.  Mrs. Mallard "knew that she would weep again when she saw the kind, tender hands folded in death; the face that had never looked save with love upon her [...]."  She doesn't take issue with him,...