Regardless of whether you get an official one.

The prenup is your state's divorce laws. If a divorcing couple cannot come to a agreement, your state laws will adjudicate the divorce, placing your assets into what is called a divisible marital asset category.

For those with significant assets, children, serial marriages, etc., it may be wise to steer this one from the onset lest they end up years later in in divorce court and allowing the state laws to dictate the settlement.