I have always found it interesting how concerned people are about who unfriends them. I have seen very upset posts on Facebook with people asking “who unfriended me.” An odd post, since if the person unfriended you, he won’t see the it. I am not sure if it is the term friend that gets people upset, but there it is.
Now, none of these services actually provide a tool to help you find out who unfriends you, but there are some external tools that can provide this information to you. This blog post by Digital Life Today does a great job of explaining some of those tools.