It is in Chapter 16 that the first change in Therese is made explicit. Following the death of Camille, Laurent begins to spend more time around the shop, helping Madame Raquin and Therese with various things and spending time with them in the evening. This is how Therese responds to this change in their living situation:
Therese peacefully watched the activity of his movements round about her. The pallidness of her face had departed. She appeared in better health, more smiling and gentle.
In a sense, the death of Camille and becoming a widow has freed Therese from a situation that was unhealthy for her and made her unhappy. As a result, she is much more at peace in herself and she can be the person that she wants to be without feeling inhibited by her husband, as she once did. Naturalism is a school of literature that explores the impact of the environment on characters, and in particular the way that their character is shaped by their living situation. The change in Therese as a result of her husband's death clearly establishes the way that his character and what he did to her life was so destructive to her and how it impacted her character. Without him, the environment in which she lives is very different and she is much more at peace and even able to begin to flourish as a character.