if he was sexually abused as a boy then your not respecting his boundaries may have been quite triggering for him. if anything it's good to be extra aware of his boundaries considering his past and to not push someone who was abused. obviously, his reaction of getting up and leaving was a bit insensitive but not all that surprising with his history. i'd apologize to him if you haven't already. i realize you are young so you may not be as aware of how this affected him. just try to be more conscious of it in the future.