How does Jill prove to be a good friend to Rose in the novel, The Nine Lives of Rose Napolitano?

Jill is one of Rose's colleagues and closest friends. For a time, the two bond over their mutual disinterest in having children. When Jill learns how much pressure Luke is putting on Rose to have a baby, she becomes cold towards him. She always listens to Rose, and supports her. She encourages her to leave her marriage if that is best, and does not judge her, even when she learns that Rose is having an affair.