My 3 1/2 year old son ask me to play in his imaginary games and I play with him. I never see any other moms playing with their kids though and the other kids also flock to me to play, but not necessarily my son. And one time a little boy was overbearing in wanting my attention he began to push my son. When I look to see the other mom's, they are usually just sitting and/or on their cell phones. I want my son to play with other kids, but he always asks me to play with him and I feel like I am denying him this simple request. He does sometimes play with other kids at the park, but usually if we already know them. Should I be encouraging him to play with others or is this behavior normal?