There are few more sensitive topics in family law than that of a prenuptial agreement. As its name suggests, it occurs prior to the nuptials, and yet its topic is the division of assets as a result of a divorce. This is conceptually a difficult idea to wrap one's head around, but that difficulty pales in comparison to the difficulty of emotionally comprehending dividing and protecting your assets before you promise to remain married "'til death do you part."
And not everyone needs a prenuptial. If you and your spouse come from modest means, and neither of your parents have substantial assets that you potentially could inherit, there may be no "separate" assets that need protection.