If you have an asset or a degree that you want to protect then you need a pre nup...
In New York it is advisable to get a pre nup if you are entering the marriage with any property of value, including real estate, a business or a licence or a degree. It is even more important if you are attending law school or medical school. A pre nup will protect you against your degree or business becoming marital property.
A pre nup will protect everybody in the marriage. It sets forth each parties rights in the event of a divorce or separation.
In a pre nup the parties can agree before marriage if maintenance (alimony) is appropriate and if it is, what amount should be payed. It seems better to have these numbers set and not leave it up to a Judge at some time in the future. Generally, high wage earners want to limit the amount of maintenance they would have to pay in the event of a divorce.