In addition to the previous answer, it is important to understand that Madame Ratignolle is serving as a character foil for Edna Pontellier. A character foil is a character who, when juxtaposed against the protagonist, elucidates opposite values while maintaing equal level (peer-like qualities) to the protagonist.
Edna is individualistic, self-proclaiming that she would "never give up herself for her children." She seeks to paint, swim, have visitors, make visitors, enjoy the company of men, and to be free of all constraints put upon her by society -- including a husband and children.
Madame Ratignolle, like Edna, is married with children, but that is the extent to which they are similar. Ratignolle seeks to serve her husband and her children, and is in fact the one who entreats Edna to "think of the children" at the end of the novel when Ratignolle can sense Edna's disdain for her own life. Ratignolle also refrains from attending parties, including Edna's party to celebrate her own living arrangement, and Ratignolle is unenthusiastic about visiting Edna's new apartment because of the possible rumors that exist regarding Edna's and Alcee's relationship. Edna searches for herself through defiance, while Madame defines herself through obedience.
Madame Ratignolle is the epitome of the perceived woman's role in the Southern Creole society of the time. She is completely devoted to her husband and children and serves as a kind of counterpoint to Edna's desires. She and Edna stand as stark contrasts of one another in many ways. Adele is warm, generous, and certainly fun-loving but she struggles in trying to understand many of the ideas that Edna confides in her. Adele draws her identity from her husband and children and simply cannot imagine a world where she is not attending to their every want and desire. Adele believes all women should believe and behave in this regard toward their families.