If the force of gravity exerts on Earth by the sun is equal to the force of gravity the Earth exerts on the Sun, why is Earth motion is greatly affected by the sun's gravitational pull?

In "the yellow wallpaper" what can the reader learn about the narrator from her obsession with the wallpapera that she wants to leave the houseb that she is becoming insanec that she is starting to feel betterd that she is upset with her husband