Maybe buy her a pillow of her own? I would suggest a nice soft dog bed but it sounds like she prefers pillows! I know they tend to like to use the same things we use. Maybe put a pillow just for her on the couch. One that can be easily replaced if she decides to much on it or drool.
I had a queen size pillow on my bed for my injured knee to rest on. Gracie was sure it was made for her so now she lays on the pillow as she watches TV on a bed that is already extremely comfortable.
