My best friend and I used to be so close before. But now, she's starting to hang out with different people and we don't spend as much time together anymore. Sometimes, it feels as if she's saying things behind my back. However, it's not always like this; sometimes we're laughing and smiling. What should I do? I have talked to her about this a little, and she said that she feels the same way towards me. What's the next step?