I think what you say is totally understandable and not as exclusive to NPD as you think. We live in a world where everyone thinks and takes care of themselves there are actually few who can really put themselves in someone else's shoes some people find it easier than others. I also think regarding getting mad and not understanding it causes pain is again normal - obviously rages and abuse are another thing But if on reflection you can see you have hurt someone and are really sorry then that is ok too!