Hereafter by Jody Hedlund
I have really enjoyed reading about the lost princesses. Emmeline had lived as one of the lost princesses and had tried to keep a low profile and not get discovered. When she realizes it soon might be possible,she tries to do what she can to prevent it. Unfortunately she is captured and forced to marry the prince. She continues to do all she can to get away, but the prince wants to take his marriage seriously and tries to make it work. All of this is also taking place as an actual battle is going on around them.