According to Francesca what motivates her descent into sin?

Francesca's descent into sin is primarily motivated by her intense passion and desire for love. She is deeply influenced by the romantic ideals portrayed in literature, which lead her to fall for her brother-in-law, Paolo. This overwhelming emotional connection, coupled with the thrill of forbidden love, drives her to act against the moral boundaries of her marriage. Ultimately, her longing for connection and the allure of passion overshadow her sense of right and wrong.