My son did not receive an invite for his "best friend's" birthday party

Some background, my son (8) started a new school this past year. He has ADHD and has some difficulty making friends. We have him participating in socialization groups, but it's something we continually work with him to improve. At the start of the year he made friends with one of his table mates, a very sweet boy we'll call Jon. My son and Jon seemed to get a long very well, the teacher said they had become great friends. But as my son has done before in his previous school, he can become clingy when he finally makes a friend he really likes. Although he and Jon remained good friends, with the help of his teachers, we encouraged him to make new friends as well. From the feedback that I gathered from his teachers, he seemed to be doing OK by the end of the year and had indeed started to expand his friendship group. He even had a couple of play-dates with another classmate and was invited to two birthday parties. Throughout the year, both I and my mother (who picks up my son after-school) reached out to Jon's parents to try to set up a play-date, with no response. I figured that some parents are busy and have weird feelings about play-dates, I didn't really make anything of it. I, too, work full time and have other children, so all this coordinating of social gatherings can be hard. I've also never seen Jon's parents at any of the parents' meetings/events at school to have an opportunity to introduce myself.Jon and my son are attending the same summer day camp this week. My son was very excited to see Jon this Monday after a few weeks of school being out. Later that day after I picked up my son, he asked me why he didn't go to Jon's party. My heart sank. This actually has happened to him before at his old school, where friends of his talk about a birthday party that my son was obviously not invited to. I checked my email, my junk folders, logged into my evite accounts, and saw nothing. My gut is telling me that there is no way this was a "lost in the mail" situation. I guess they had a whole conversation about it and Jon went into detail about how the party started at his house and then they took his friends to the science museum. He even mentioned the children from their class that did go. My son was pretty upset and thought that it was me that didn't take him. So r/parenting, I'm not sure what I'm asking here. My son still really loves to play with Jon. We live in a big city where children from all over town go to this school (we don't live in the same neighborhood), so social gatherings usually have to be coordinated by parents. I was thinking of trying to reach out to his parents one more time and see if I can set up a play-date, but am I just barking up the wrong tree? My husband said to just leave it alone (he too was heartbroken for my son). Maybe I'm the one more upset about this than anyone, but for a whole year we heard about how much he loved playing with Jon. Even on the last day of school they gave each other a great big hug and talked about arranging a play-date, so it gave me a great warm feeling that my son was finally making some breakthroughs. via /r/Parenting http://ift.tt/2rNGb5X