My suggestion should be the agreement between two couple whether they are married or not, they must have some kind of contract and rules before they became associated with each other, if they violated the rules there must be some kind of punishment and the custodian as a mediator. Though as you mentioned; when there's a time that people will evolved into some kind of liberated person and they no longer care being naked, Some part in Europe has a night club that only allows to enter are those naked.