What are the significance of Norah in The Memory Keeper's Daughter by Kim Edwards?

Norah is a sweet and innocent young woman when she meets David Henry in a department store. She has fairytale dreams of how a marriage should be, and she is very much in love with David. When she learns that her daughter died in childbirth, she wants desperately to see the baby, but accepts David's explanation that he has already taken care of having Phoebe's body buried. Sensitive and grief stricken, Norah feels Phoebe's presence in the edges of her consciousness throughout her adult life, and mourns her loss, perhaps, more than most people would mourn a stillborn child. Although she is delighted with her son, Paul, and appreciates him deeply, she is haunted by the loss of Phoebe. Even more upsetting is the loss of David, emotionally. David has withdrawn from her and she has no idea why. She would like more children, but he objects. As David retreats behind his camera lens, he begins having Norah pose for him, trying to create images of her blending with nature, blending with the background, so that one can barely make out the fact that there is a person in the photo. Norah feels objectified, since the photos are not of her as much as they are of her body as a prop.