In Walzer's cynical view, these clauses do little more than provide a "powerless" person with the feeling that they got something in a relationship agreement worked out with a more powerful partner. And that's because courts will in most cases disregard these clauses, said New York City divorce attorney Robert Wallack. "They're used to set forth relationship expectations, not contractual obligations," Wallack said.
Walzer said there is also a risk that one unenforceable clause leads a judge to invalidate an entire contract. It's unlikely, but it's imperative that any relationship contract that includes lifestyle clauses explicitly states that in the event an isolated clause is deemed unenforceable, the broader contract is still in effect. The legal term for this is severability.
"Any good contract says that if there are parts that are deemed unenforceable, it will remain in effect in other parts of the contract," Carrozza said.
The legalese may be confusing, but Chicago family law mediator Michele Lowrance said the heart of the matter is understandable: Relationships are hard. She is seeing more prenups and said the contracts are bound to get even more creative and expensive. "Everyone is at such a loss when it comes to relationships, they are looking for any reason to make them sustainable," Lowrance said. "The more communication, the better, or there will be more trouble later."
However, the retired family court judge said there's a basic risk of putting anything into writing—it can come back to haunt you. Lifestyle clauses on their own may be unenforceable in court, but it's still written ammunition for an angry spouse—especially if there is a divorce proceeding.
—By Constance Gustke, special to CNBC.com