T.C.
I think it's a combination of age differences - both in development and idiosyncrasies. After playing with the younger child (your son) for awhile, the older children may simply want to play in an "older" (3&4 yr. old) fashion. Plus, having a 4 yr. old daughter I've noticed that starting at about age 3, she started having all kinds of attitude that was much worse than any terrible-2. What was great for her a minute ago, is suddenly not OK. So, it may just be a phase for the older children. Finally, after hosting many playdates for my moms group, I've noticed that 1 to 1 1/2 hrs. is about all the kids in the 2-4 yr. old age group can handle. After that amount of time they start getting cranky, arguing, fighting, etc. I think the fact that the older children start out playing with your child shows that they like him and want to play with him. I wouldn't worry too much about it and I wouldn't give up the friends - it's MUCH harder for us moms to connect with friends than the children!! :) I think it's just a phase. Try to direct your son toward more individualized play (puzzles, blocks, etc.) when the other kids start needing "alone time". Also, you could ask the other moms if there is something that your son is doing that their children don't like. They may be able to give you a little insight. It's super hard to watch your child be rejected by other kids, but they seem to work through it pretty well themselves. Enjoy your mom-time - it's great that you have a circle of friends!