I think what hurts the most is that someone will possibly never know how they hurt you. It may also take some time after whatever happened to realize, there is some pain from that but at the same time as soon as we feel that pain we must also see it as a sign. A feeling always comes with a sign, but we focus more on the pain, on the feelings, instead of what it means. In this case feeling pain from someone after doing something only means I must love myself more. It happens so often and we make a negative connection and we feel negative, we do negative actions and it makes it all worse.