If you only have a few friends on Facebook, it is easy to keep track of who is being friendly and who is not, but when you have hundreds or thousands of friends, it becomes a little bit more difficult and that is when you could do with some help.
Check out this Unfriend Finder extension for Chrome, it is an easy install and it will show you just who has decided not to be your friend anymore. Of course, you should not take it personally, just move on to the new friends who are just waiting to connect!
Here is how you install the Facebook Unfriend App;
Install Unfriend Finder from here
Page will automatically figure out what kind of browser you use, and will give you relevant instructions for installation (my suggestion: use chrome, is the easiest way to install the extension)
Restart your browser and you will see a small icon near the Facebook chat (-1), and Unfriends option on the top (right side) of your Facebook profile.