E L James 
Fifty Shades Duo: Fifty Shades Darker / Fifty Shades Freed 

The final two books in the phenomenal Fifty Shades trilogy
Fifty Shades Darker
Daunted by the dark secrets of the tormented young entrepreneur Christian Grey , Ana Steele has broken off their relationship. But when Christian proposes a new arrangement, she cannot resist. Soon she is learning more about the harrowing past of her damaged, driven and demanding Fifty Shades than she ever thought possible.
Fifty Shades Freed
Anastasia Steele always knew that loving Christian Grey would not be easy, and being together poses challenges neither of them had anticipated. But, finally together, they have love, passion, intimacy, wealth, and a world of infinite possibilities.
Then just when it seems that they really do have it all, tragedy and fate combine to make Ana”s worst nightmares come true…