She could never escape.
Mistress's special scent stayed on her all day, reminding her that she was owned and helpless. Mistress made her reapply it throughout the day and sprayed it throughout the house. It was even soaked into her clothes. Even if she tried to leave, what would she wear?
One time she had gathered all of her will to try and wash it off, only to find her hands disobeying her. Instead, they went to one of mistress's spray bottles and covered her body with the scent again. It was then that she truly realized: She was trapped.