Rose was feeling very ashamed of herself in front of Lucas. She had never imagined that he might have knew about her secret hobby of reading those naughty articles. But who is at the fault by the way!
She really wanted to make Lucas feel good, and when he hurts her punishment is must. Afterall this all she is doing is only because of him and only for him. Because she knew she is very very inexperienced in this field while he on the other side is already very experienced. Example is here at her front who is now saying her that he will do those things with her which she neither ever read nor ever imagined. This means the only thing that he is very experienced and she is not. And it's what she does not wants him to think about her.