Demons question

(The book I have linked is not the book, I couldn't ask a question without linking a book) I read a book years ago and I loved it then. All I think I remember about the title is that it was, a girls name demon. Ex: "Sarah's Demon". The story is about a girl that forgot how to love and be loved. So a demon comes into her life and shows the girl her past lives with him. They lived in different eras and even looked completely different but they always seemed to find each other. Well each past had some sort of horrible drama in it, so the girl in her current life, closed herself off of love. That is until the demon comes into her life and shows her how to love and be loved again. I have been searching for this book for the last 2 years. I really hope someone can help.