It is hard for him, really, in many ways he is like an only child, he has Brothers, but they are in their twenties. So he hasn't had much of the normal, rough and tumble play that you get with siblings. Play at school or on play dates is pretty well monitored so rarely gets physical and never violent. Football is a game of controlled violence and that's really not been a part of his life so far.
He gets frightened and angry when people hurt him and there's a fair bit of that in football, even flag football. Most of the other kids have learned to work past the painful moments and "walk it off" but Boy hasn't yet and SWMBO is horrified by the whole thing.
Still Boy says he likes it. We'll see how it goes.