My almost-four year old boy has been expressing concerns recently that some of his close friends don't want to be his friend any more. While I'm aware this sort of drama is perpetual in childhood, I think he has some specific concerns that we need to help him address.
1. Being Pushy
He's a very pushy child. I don't think most children his age have a fully developed sense of empathy1, and most are still fundamentally selfish, but he's definitely more pushy than most other children his age. He tells other children how to play, and complains when they're not doing it right. He wants to play with a certain toy and gets very mad when someone else is playing with it. Occasionally he'll grab toys from others, although we've mostly worked that out (or age has).
There are a few other children who are probably innately as pushy as my son, except for one thing: he's quite big. He's 42" or maybe a bit taller now, which puts him for a 4 year old in the 95th percentile. This means that he's physically able to dominate the other children around him that are his age, and it also seems to give him the confidence to do so. If he wants to take a toy he can do it. He's faster than most of them, he's stronger than most of them. 2
2. Being selfish
In addition to being pushy, he's definitely still quite selfish. We set up a playdate the other day, and he liked the idea, but he also said that he didn't want [friend] to play with his trains. (He has maybe a hundred wooden trains.) I tried to talk about it more, and he just didn't seem to get that his friend would want to play with trains and it would be rude not to let him. I tried my usual tactic - asking how he'd feel if he was at his friend's house and couldn't play with any of his toys - but it didn't seem to get through. When the playdate did occur, the friend basically parallel played with my 2 year old's toys (who was at daycare).
All of this adds up to the fact that the selfishness and pushiness means he doesn't completely understand why his playmates don't want to be friends with him. He's noticeably sad about it - enough so to tell me, out of the blue, that he was sad about it - but he doesn't really get how to fix it.
How can I help him fix it? What can I do to help him understand what he needs to do to be a better friend?
1As a side note, this is the same preschooler from this question, and we've worked on it some in manners similar to what @anongoodnurse suggests. That's seemed to help, so it's possible more of that is what's needed.
2 Playing with older children seems to change this dynamic dramatically, which is part of why I think his size matters (though it's not the only difference, of course). He plays very well at the park when he finds a random five-to-six year old (in particular, a girl) to play with, and will clearly limit his pushiness and usually follow the child around to some extent. Some of this could well be emotional maturity - either the ability to cope with pushiness, or the knowledge of how to overcome it.