When you’re on Twitter, it’s easy to know who's following you. As soon as you gain a follower, you are informed by email.
On the other had, if you want to know who doesn’t follow you anymore, things become more complicated.
Fortunately, there is a solution.
RSS Friends allows you to track your followers and unfollowers under the RSS tracking system. Subscribe to this generated feed and voilà, you know who has got bored of following you...
But why would you want to know this anyway?
Firstly, it allows you to analyse the impact of your tweets on your followers. Furthermore, knowing the people who no longer follow you means you can sort out your list of followings (people who you follow).
For more info on Twitter, please see Twitter: how does it work?