In these types of novels, a central theme is the power of love itself. Love is what drives the wife to stay with her unconscious husband, through all the difficulties. Another theme is the test of time. Since his recovery may take a long time, if ever, their love is put to the test. This can also lead to the theme of transformation. The wife may transform from a dependent person to a strong and independent one as she faces the challenges of taking care of her husband. And there is often the theme of the unknown. She doesn't know if he will wake up, what state he will be in if he does, and how their relationship will change, which adds an element of suspense to the story.