DD (5) most likes 2 girls in her class who are very good mates with each other, and never that friendly to DD. They are friendly to other girls in the class, just not DD!
This has been situation for almost a year, I tried (often) inviting the 2 girls around for playdates, but they never come.
Recently the 2 girls had birthday parties and DD not invited. At some point DD may notice that these girls aren't interested in her friendship... if she's upset, what do I say? Thankfully she does have other friends.