So why is she inside? What keeps her there? There is a wistful look that hints that she wants to be outside, but we don't know why. The environment is more important than the subject in something like this. The idea is to see how the environment affects the subject (defines them) and how the subject interacts with their environment. We see the later, but not in a context that defines "why".
An environmental portrait is a portrait executed in the subject's usual environment, such as in their home or workplace, and typically illuminates the subject's life and surroundings. The term is most frequently used of a genre of photography.