There are not a lot of things you can’t include in a prenuptial agreement. One of those things I talked about in previous posts were provisions regarding children. Another one are provisions regarding sex during the marriage.
I have had requests to include provisions dealing with a sex schedule for the couple. In those cases, I tell them that it can be included, however it cannot be enforced. If a husband sued his wife for breach of contract for not abiding by the sex schedule, a judge will rule that provision invalid in the prenup. This is because to condone it or to enforce it (legally called specific performance) would mean that the Commonwealth of Massachusetts condones rape. You cannot force another person to have sex even if they’re your spouse and it’s not a right you can contract.
In almost all prenuptial agreements and in most contracts, there is a severability clause put in which states that if some parts of the contract is ruled invalid, it does not invalidate the entire contract but instead, the invalid portion should be removed. If you do have some sort of sex schedule included in a prenuptial agreement, make sure it also contains a severability clause.