The very idea seems like a contradiction in terms, but Mexico City is actually considering it:
Mexico City lawmakers are proposing legislation that would allow newlyweds to apply for temporary marriage licenses, instead of making the plunge into wedded life a lifetime commitment.
The change to civil code was proposed this week and would allow couples to decide the length of the commitment, with two years as the minimum. If couples are still enjoying wedded bliss when the contract ends, then they would be able to renew the license. And if they’re unhappy, the contract expires and they are both free without going through a divorce.
This has been proposed by politicians and writers in The Philippines and Australia, too, so don’t be surprised if someone raises the issue here in Canada. Leaving aside the moral question, I’m curious to know how property division and other corollary relief issues would be handled.