S.M.
I totally know how you feel. My daughter went through a period like that at that age also. She would approach kids and introduce herself and they would just ignore her. I even had 2 girls at Chickfila tell her they did not want to play with her they hated her. Little brats!!!! It broke my heart! You might try and point him toward someone his age and also a single kid, they seem to be more approachable when they are alone. Just keep bringing him to the park, it does get better. There will be hits and misses, unfortunately I can't tell you how to not feel bad when other kids are mean, if you find out let me know. :):(