“There is a natural curiosity among mortal male and female lovers of vampires about the history of their particular lover. Most vampires are reluctant to reveal the stories of their undead lives because secrecy is an integral part of their survival instinct. Vampires are reluctant to reveal the details of when they were turned.”
In The Vampires among Us by Thaddeus Romans
In my vampire novel, Unholy Embrace, the mortal male protagonist wants to know the female vampire' history for the past 400 years. She is reluctant to tell him for several reasons. First, telling her story would make her relive the worst moment of her life, the night when another vampire killed and turned into one of the undead. There is also the issue of revealing secrets she has kept to herself over the centuries. Secrecy has been a survival strategy for her, and even though she loves him, telling him the details of her vampiric life goes against her experience. Lastly, there are personal details and experiences she is not ready to share. There were other lovers before him, which he need not know about. Moreover, during her long existence, the brief periods of violence interrupting decades of boredom, events which she has found difficult to accept.
http://www.writing.com/main/view_item/item_id/1639917-Unholy-Embrace----First-Three-Chapters