What has happened is that society (at least in the U.S.) has decided not to support The PromiseTM It is easier to get divorced (even over the objections of the other party in the contract) than it is to get out of a car lease.
And we wonder why men are afraid of getting married. They love their wife, are a wonderful provider, fabulous father and still find their wife has left them, taken their children and half or more of what they may have primarily earned with a note that says "I don't love you any more."
And heck, why should a man have to. With the advent of birth control, women everywhere sterilize the normal and sacred functioning of their bodies so they can make them available for the pleasure of men, risk free. And if an "accident happens", there's always Plan B, (when plan A[bstinence] always works). If plan B fails, there's always plan D & C. :P
From the comments to this post on adultery. (Via Tigerhawk)