The Other Boylen Girl by Phillipa Gregory

I love this book. It is full of small factual errors, but they all support the story. This book Is about Mary Boylen, sister to Anne Boylen, Henry VIII' s second wife, and his mistress. She catches his attention, and falls in love with him. She is pushed by her family to become his mistress, and she is willing to do that (after a short moral dilemma about her husband), but her family wants her to keep him, which was very difficult because he was like a spoiled kid, always wanting something new.

This book is a little long, but well worth it. There is also a sequel called The Boylen Inheritance.