It’s quite impossible to have a track of who unfriended you, deactivated their profile. Even if you keep a close eye of your friend count still you’d find it hard to say who.
Now there is a much easier plugin for this Unfriend Finder
Unfriend Finder is a browser script, you could install it on Chrome, Firefox, Safari, Opera, and IE. Once someone unfriend’s you or deactivates their profile it would notify you.
Once the “Download and Install” is clicked the exe file should automatically download. Click and install the downloaded file.
If you are using Firefox, you need to install the Greasemonkey add-on before you can start using Unfriend Finder.
Once installed you would find three additional features.
1. Top-right menu of your Facebook page, visible on all pages.
2. Left menu of your Facebook Wall
3. Bottom icon button next to Facebook Chat, visible on all pages.
Happy Unfriending! And if you ever try this plugin please leave your experience below as a comment!