This has nothing to do with books, but my (now ex) wife and I met another couple many years ago, and we were friendly for a short while until they moved away.

This has nothing to do with books, but my (now ex) wife and I met another couple many years ago, and we were friendly for a short while until they moved away. A year later, my wife got an itch to talk to the other wife. She had no address or contact info, but my wife was part bloodhound at this sort of thing, remembered her mentioning her parents in another state, and eventually tracked them down to see if she could get the other lady's contact info. The other lady called my wife back... and the conversation went something like "how did you find me? Please don't ever contact me or my parents again, just pretend you never met me, and please, please, don't ever let my husband know where I am."