Popularity Contest?

When I was younger I had a small group of friends.  We were inseparable, we did everything together.  But there were times when I would not be invited to things. I felt left out, like they were mad at me or just didn't like me any more. When I grew up I thought to myself, I want my kids to someday have a group of friends that will love to be around them. I want them to have play dates and go to each other's birthday parties. I want them to feel included. 

Sometimes, you don't always get what you wish for.  I find myself feeling awful for them when they don't get invited to play dates or birthday parties.  They see what is going on and they know when they are not invited, they then cry to me about it and my heart breaks.
What am I supposed to say to them? How do I ease that hurt that they feel? I sometimes just do not have the words to make them feel better.  All I can do is simply cuddle with them and let them know everything will be okay.  Sometimes I cry with them.  It brings me right back.

Yes, that was in my past, but when you have children, you want everything for them. You want them to be happy and loved.

Today my heart aches because it has turned into another one of those days.  Though in a strange way I feel like it's been a slow process in the making.  It's strange to say, but I feel like I've seen it coming.

I just hope that my kids will bounce back from this, myself included.  I want nothing more than my kids to be happy and love life and the ones in their lives.