There is always, and I repeat ALWAYS, one very upset spouse in a divorce where a PreNup was signed. No matter what you are told, the reason your spouse is asking you to sign a PreNup is because they want to give you less then you are legally entitled to.
Every PreNup should have a "sunset clause," stating that once you are married 'X' number of years, it becomes null and void. This is the only way to equalize what you are waiving, which is usually alimony and money for an attorney to represent you in a divorce. It could be that at the signing of a PreNup, you are an emotional hostage at your wedding time. Do not sign a PreNup unless you have an experienced attorney negotiate a very fair one for you!