Which is the importance and function of the Lucrezia in Septimus's life?

Septimus' wife, Lucrezia lived in Italy before marrying and made hats with her sister. She is young and fun loving, but becomes seriously humiliated and sad when Septimus starts slipping into insanity. She wanted a normal marriage with children, not a man who talks to himself. When they first met, he had introduced her to Shakespeare and listened to her. Rezia tries to protect her husband from the doctors, but, in the end, she cannot.