“Is there a way I can tell who unfriended me on Facebook? When my number of friends goes down I want to know which people unfriended me.”
A number of applications promise to track who unfriended you on Facebook or who de-friended you on Facebook, but they frequently either stop working or get banned from the application list, so you might have to add a new one periodically. There are currently about 6 applications available. I’m not listing them here only because I expect they will be cancelled and new ones will pop up in their place. Instead you need to do a search.
To track down which apps are available to track who unfriended you on Facebook, type either unfriend or defriend in the search box. When you get results back, click on Applications in the left side column, which shows you the available applications. You may have to try a couple of them before you find one that actually works because these are kind of hacks.
After you install one, the only real way to know it’s working is to ask one of your friends to unfriend you. You should then get a notice that they unfriended you. Of course if it’s someone you like, hopefully they will add you back.