why did John did this to his wife?

As a physician, John believes that his wife suffers from temporary depression and a tendency to be particularly anxious. He would not normally, according to the narrator, have taken her to such a location as is in the story, but he believes, along with her brother who is also a physician, that she needs rest and a chance to recover. He wants a quiet place where she will not be bothered by anyone; he hopes that such isolation and quiet will aid her return to normalcy.