The attitude towards women, as reflected by the males, is very patriarchal. Women are treated as incapable to think for themselves and any outlet for creativity is crushed and destroyed. This is the reason why the narrator retreats into her mind. In today's society, we still live in a patriarchal society, however, women have much more freedom of expression than they did in previous eras.
Also, "The Yellow Wallpaper" is a short story, not a novel. Your teacher/professor might mark you off for not properly identifying what type of literary work you're writing about.