Why does chopin build a realist novel around a protagonist who cheats on her husband, leaves her children, and ultimately takes her life rather than submit to her prescribed social roles?

Because she wants to question the concept of feminine personality. loss of self, view of womanhood. The novel argues that male-dominated society legitimates the victimization of women, creating a sense of selflesness.

The purpose of her narrative was to show how the traditional role of women was restrictive to their individuality.  

Explanation: In "The Awakening" by Kate Chopin, the boundaries set on women to be good mothers and wives was harmful and required that women sacrificed their own identity in order to meet society's expectations. Instead letting society punish her for not being a true "mother-woman", Mrs. Ponteiller  resorts to taking her own life as a means to gain autonomy.

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