He makes love with her but rebuffs her afterward, leaving her to think she has done something wrong. Without giving too much away, I can say there is more to it than a single event, but that it involves his father, his sister, and his grandfather. To say that Christian resents his grandfather is putting it mildly. His grandfather is a thoroughly unlikable character whose treatment of Christian is unforgivable. While Christian's initial treatment of Grace leaves much to be desired, it's hard to dislike him completely when you find out the reasons for his actions.
Grace is a heroine with spunk , but in a good way.
Frankly, through most of the book, Christian is undeserving of her and a part of the reader will just want to shake her and point that out. It seems to that all she really wants is a home of her own and someplace she belongs. The story has some loose ends that should have been tied together more neatly. There is a connection between Christian's grandfather and Grace's grandmother which should have been explored more fully than it was. The reader is also left hanging a bit concerning Christian's sister Eleanor.