Who is Norah Nesbit from Of Human Bondage and what is their importance?

After having his heart broken by Mildred the first time, Philip throws himself into his studies. One day a friend asks him to be a fourth on a double date. On this date Philip meets Norah Nesbit. Norah is kind to him, kinder than any woman has ever been. Soon Philip gets into the habit of seeing Norah every day for tea. They are just friends at first, spending a great deal of time talking and sharing each other's confidences. Philip tells her about his love affair with Mildred and Norah tells him he is better off without her. Soon their friendship turns to passion and Philip finds himself in a comfortable relationship he never imagined he could have.

When Mildred walks back into Philip's life, he does not know what to do about Norah. Philip has never been in love with Norah, but he feels a great deal of affection for her and does not want to break her heart. However, Philip no longer wants to be Norah's lover. Eventually Philip finds himself forced to tell her the truth. Norah is terribly heartbroken, but she is not cruel to Philip. Norah is in fact quite kind. Sometime later, Philip goes to see Norah after he has broken up with Mildred again. It is too late, however. Norah is engaged to marry another man.