I can imagine something like this (whether publically or personal) would suck. Here is a link to one marriage proposal gone wrong:
http://www.youtube.com/watch?v=UtPkxzHKLpk
Usually men take too long to even bring up the marriage topic. But supposely what if they've been together for years (assuming their relationship was great) and wants to marry the woman as he's already ready but she says NO, I'm guessing this would crush him just like it hurts us when a woman is finally convinced her man will never proposed and doesn't feel the same way towards?
Not sure how often something like that happens but I'm guessing not much.