Isabel Sawhill discusses marriage in a thoughtful article here:

Longtime defender of marriage asks if we should try something else

My preference is a something akin to a rental agreement. The terms of the agreement may be as specific as desired. Prenuptial, separation and divorce agreements provide useful terms for the marriage rental agreement. The rental agreement could be updated, modified and enforced as any other contract.

The parties benefit by knowing at the start what is expected from them.