It's perhaps human nature to be entertained (sometimes) by other people's misfortune. We slow down to look at car accidents, laugh at the Darwin awards, and watch soap operas (well, I do two of the three at least).
Likewise, here's a video collection of failed marriage proposals. These guys get seriously slammed!
I have sympathy for them because of the ambivalent response I got from my wife when I asked her to marry me. We had been dating for about 6 months, and I knew that I wanted to marry her. I didn't know if she was ready to say "yes", but I thought I would ask. Well... we were visiting the Gettysburg battlefield (she's a historian after all), and we had a late afternoon picnic overlooking the location of Pickett's charge. I figured that spot had been good for northern males in the past, so why not now. So, I popped the question.
I think that she went through the five stages of grief (denial, anger, bargaining, depression and acceptance) in about thirty seconds, and then stammered out how nice it was that I asked her and how unready she was to answer. So basically, I got a marital "revise and resubmit."
The funny thing is that I took before and after pictures, wanting to commemorate the happy occasion. Before, she is beaming at the romantic picnic in such a wonderful place (for a historian), and afterwords she looks confused and sour. (When I show them to people now, I just switch the order!)
P.S., happily she said yes a couple months later.