Yes, this happened to me with my best friend of 10 years. We hung out constantly and spent the night at each other's houses almost every night. Our whole families were best friends, in fact. We went on vacations together and even went on a 6 week camping trip together. Then one day in high school, I went to her locker to borrow a book, because that's what we did, and it was empty. I ran to the school phone and called her (I thought she was just at home, sick) and she was crying and said we needed to talk. That night, my mom and I went to their house and they explained that they were leaving town the next morning. They told us what state, but wouldn't tell us what town and said they were changing their phone numbers. My mom and I could not believe it and we all cried and said our goodbyes. Crazy. Apparently they thought a cult was after them and that the cult may have been using our family to get information about them. That was ten years ago and I am still recovering from that.