I agree...give them time and don't interfere. As hard as it is, our kids need to learn how to handle their friendships themselves.
My DS is 10 and he has had the same bunch of friends forever, however over the last couple of years there's been drama. One day he hates Chris, the next day Chris is the best thing ever...same thing with Nicholas, and Foster, and the rest of them. As they grow older they start to grow apart because they are changing. It's totally normal.