Couples in Mexico City could soon use "renewable" marriage contracts to try living with their other half before making a lifetime commitment.
Newlyweds would take a minimum of two years before deciding whether to cement their relationship or split up, under plans to alter the city's civil code.
If approved, the contracts would set out in advance marital duties, such as in childcare, schooling and budgeting.
Lizbeth Rosas Montero, who drew up the bill, hopes it will cut divorce rates.
Half of all marriages in Mexico City currently end in a split.
She believes the contracts, allowing couples to "renew or dissolve" the marital link after a pre-arranged term, would lead to more harmonious relationships and reduce the workload on family judges.
Terms governing healthcare provision, the way children are educated, how much money was needed to support the family, and how dependents would be looked after in the case of a break-up would be set out in advance.
Ms Rosas says families would then avoid the usual wrangling and emotional upset if they did break up.
"If within the two years the spouses decide the marriage isn't working, they can divorce in the traditional way. No-one can make them stay together," said Ms Rosas, a social worker.
However, the bill has attracted criticism from families campaigner Consuelo Mendoza.
She attacked the initiative as contributing to a "throwaway culture" in respect of society's institutions and said it would put children through the anguish of wondering whether their parents would stay together.
BBC Mundo's Ignacio De Los Reyes says the bill, which also sets out rights for common law couples, is likely to go before legislators in December. Its backers are members of Mexico City's governing PRD party, which has a clear majority.
However, the party is divided and - as the plan requires complex reform of the civil code - it would be difficult to convince all PRD legislators to vote together, he adds.