Why does Desdemona continue to continue banter with Iago despite his harsh words?

Cassio greets them all, especially praising Desdemona; somehow, Iago and Desdemona enter into an argument about what women are, and Iago shows how little praise he believes women deserve. Iago is trusted by Othello so Desdemona remains civil to him. Desdemona is also very kind hearted and does not hold a grudge easily.