Since these are rule of law treaties under national contract law, both contracting parties must be legally able to sign the treaty. This does not necessarily mean that both spouses must be physically able to sign their name, but they must both be at least 18 years old. As of 2017, only four states (Nebraska, Ohio, Oklahoma and Wyoming) do not impose or strongly advise against postuptial agreements. Yes. Sometimes post-client contracts are designed with an end date in the initial agreement. For example, an agreement could provide that if the couple is still married 15 years after the agreement is signed, it will be void and not foreseen. This proposal for a terminated contract offers a good place to start, but you should ensure that it is applicable in your state or country and, if in doubt, it is worth consulting the legal counsel. . .