I'm going to guess it's due to due to my girls being extremely shy, but they have a hard time playing with other kids. At the park for example, they stop playing even if other kids show up! I try and help do intros and get them to play but they just won't have it, they are missing out on so much fun! Is this just a phase that they will eventually grow out of, or more of a personality thing? Anything I can do to help?