But Facebook won’t notify you when people remove you from their friends list but if you would still want to have that data.
there’s a web app called Twenty Feet that can help reveal the names of your ex-friends.
The idea is simple. You connect your Facebook account with Twenty Feet and it makes a note of all the Facebook profiles that are listed as your Facebook friends. It fetches this data every day and alerts if it finds one or more connections that have gone missing from your Facebook friends list.
There are two possibilities – either the person has quit Facebook altogether or they have unfriended you for some reason. Other than Facebook, you may also use Twenty Feed to track your lost followers on Twitter
Twenty Feet takes a freemium approach – you can track one Facebook account and one Twitter account for free
The following video will show you how you can use TwentyFeet to find out who has unfriended you on Facebook. Obviously, it can only track friends that have deserted you after you have joined the Twenty Feet service.