There are some pretty powerful themes in the story, and they are made pretty clear in the summary below. The coming of age theme is one that winds its way through all different places in the story and connects clearly to that of sex and added responsibility. As she goes to the castle, the journey might be considered a symbol of that transition, but it also starts the entire set of actions that drive her coming of age. The consumation of her marriage which starts her curiosity about sex and her use of the various roles of sex in her life continues to drive that theme of coming of age. It also begins to show the fact that she is not entirely innocent as she begins to delve into things that aren't considered appropriate, etc.
Un fortunately i haven't a total accesss for enotes which is required to find the answer of my question about themes, so you will be thankful if u can get them for me of course if u have a total access.