Indeed, Jane almost seems fearful of John, as she is not able to "say what she(I) feels and thinks in some way" and writing is "such a relief". This however contradicts her statement that John " loves me(her) deeply", which she says in a tone of one trying to convince oneself. Her behaviour is very ironical, as a person should feel most at ease with, and not the opposite, when around somebody that loves them. It is also very ironical that John should say that "no one" but the narrator herself "can help her(me) out of it" and that she has to use her "will and self-control" when his actions all serve to suppress her very will and control.
As a result, Jane largely gives one the impression that her actions and thoughts are dictated. While she may have physical freedom, able to "walk a little in the garden or down that lovely lane- albeit not that much, she is mentally limited by the invisible shackles formed by her environment that causes her to tire easily and have to "lie down ever so much" despite her dislike of the wallpaper. Her description of the bed as "nailed down" also creates the impression that she herself is being nailed to the bed and this could be a metaphoric explanation for her perpetual weariness.
There is a repeated emphasis on the weariness of the narrator. The words "tired" and "exhaust" were used many times throughout the short passage and she also describes herself as "fretful and querulous", which are all signs of tiredness. Tiredness could perhaps also be seen as a metaphor of the narrator's mental state. She is mentally weary at having to 'battle' with her illness and is weary of being treated like a child. Metaphor aside, the harping on her physical lethargy certainly emphasises her fatigue and this contrast starkly with the seemingly boundless energy that she displays when examining the wallpaper as well as her child-like behaviour.
This hidden energy and character surfaces once in a while, especially when John is "kept in town".