For some reason Sam had always had pretty good self control. Probably because he'd always dated girls he knew he would have to take it slow with, and their relationships always seem to end before anything real consequential happened. Maybe it was self inflicted punishment, but probably not. He was typically a nice, do-good kind of guy. And his grades weren't ever so bad that he required such punishment either. Maybe it was fear. Maybe it was an accident. It never made him feel terribly bad--or good for that matter--for being a gentleman. Except when he factored in that he was probably the only guy he knew that was still a virgin. It wasn't for lack of trying. More of a lack of opportunity. Which was different, really, when you thought about it.
That being said, he wouldn't be totally opposed to her taking his shirt off, mostly because there really wasn't anything to hide. He worked out, he played two sports, and the way her fingers were pressed into his back felt really good. His arm dropped to around her waist and he tugged her closer.