My 4 yo ds has stopped wanting to go to school/camp and I think I finally figured out why. According to a teacher, a boy in ds's class told my ds that he is not his friend. That apparently bothered my sensitive ds so much that he has decided to withdraw from all socializing, whether with kids who clearly want to be his friend or this kid who doesn't. I realize my ds is more sensitive than the average kid. What's the best way to deal with this situation? And how can I toughen up my kid a bit so he isn't so bothered by random meanness which he will encounter throughout his school career?

• New York City