While it doesn't cover all the relationship status changes, the Break-up Notifier (http://www.breakupnotifier.com/ http://www.breakupnotifier.com/) provides par

While it doesn't cover all the relationship status changes, the Break-up Notifier (http://www.breakupnotifier.com/ http://www.breakupnotifier.com/) provides part of that functionality. Arguably the most useful part :)