My 7yr old son has decided to play with only girls at school. He was teased but the school has dealt with that and he is now happy and doesn't like it when other boys try to enter their play as he thinks his role is being taken away. He is in the footy team and is very keen to interact with his peers outside of school but has always had difficulty finding a solid bond with other boys. We have tried the take a ball in approach, it worked for one day but he prefers the girl pretend play. I suspect he has had so many rejections from the boys at school that it is all too hard and he would rather hang with the girls because their nice to him (he does have an 11yr old big sis & baby brother) He is not effeminate but does have some odd behaviours eg flaps his hands and talks in a baby voice when excited or nervous.
My concern is that boys interact in very different ways to girls and he is obviously struggling to understand the idiosyncrasies of male friendships, will this affect his ability to relate to men in the future, he will be attending an all boys high school but that is 4yrs away. I am considering boy scouts and have asked his teacher to see if she can find a boy in his class that might be a good fit and encourage this relationship.
I think you are right in saying he's struggling to understand how other boys interact and connect with one another. I myself felt the same as a child, often hanging around the girls as i felt more comfortable around them (and having two older sisters). I always felt the other boys were too rough and was intimidated by that.
I did however, develop connections with other boys eventually and believe that abit of growth and maturity will assist that. I don't think it's a cause for concern just yet, he will develop those connections and wont see hanging around girls fun or interesting anymore. definitely try him scouts or something else, but i think it's going to be something that works itself out in time.