When you get RSVPs that are "no" from people you really want at your wedding.
One of my dearest friends (and a college roommate), sent me her RSVP card yesterday with "will celebrate from afar" marked on the back. I knew she and her husband were on the fence - they live about 3.5 hours away and is 1/2 way through her first pregnancy. Baby has made her very sick and they are worried about traveling next month. I gave her an extended deadline, but they decided to go ahead and decline..
So I'm a little bummed.