The word "sex" is never mentioned in The Awakening except as it refers to gender.
Kate Chopin’s husband died, leaving her in a huge amount of debt (over $200,000 worth) and with several small children. She was a passionate woman and engaged in an affair with a married man before moving to St. Louis to live near her mother. Later she suffered a nervous breakdown and began writing as a way to cope. This led to her career as a writer.