The need for self-fulfillment causes her to leave her husband, which was not acceptable during the time the novel takes place, to be with her lover that refuses her, due to society's thoughts on divorce.
Each of the chapters plays on the previous and leads to the next in a chronological order, starting with the realization of her mundane lifestyle and each chapter showing a new sense of rebirth.
The entire novel centers on Edna Pontellier's crisis of realization of what life is lacking. Edna is an attractive young woman who is marvelous at art, and strives for a career as an artist - her only means of self-expression. Much of her life is spent in turmoil over her perception of life and it's lacking of satisfaction. Near the beginning of the story, Edna finds herself dissatisfied with her marriage and realizes her entire life had been lived through others, all male, and she thus begins to question life.
Leonce Pontellier is Edna's husband, who is a wealthy older businessman, perceiving Edna as one of his many possessions. Though Leonce believes he is treating Edna with total freedom, and is a model husband of the time, Edna still feels trapped within her life because Leonce does not understand her in the slightest, or her need for independence.
Robert Lebrun is what people now refer to as a 'home-wrecker,' attaching to a married woman each summer at his mother's summer. This particular summer he attached himself to Edna, causing her to fall in love with him. Robert is constantly toying with Edna's emotions, running away to avoid an affair, returning to confess his love, and then leaving again to avoid his own humiliation when Edna left her husband for him.
Adele Rantignolle is a static character; she shows no change or growth from the beginning of the novel to it's end, and is also somewhat simple. She is a close friend with Edna, and in fact it is her conversation that began Edna's awakening.