I would like to marry you for a timed period, for that's the legitimate resolution for us. In this marriage there's an affirmation side, that's for a woman to say "I marry you for a period of such and a dowry of such". There's also an acceptance side, that's for the man to say"I accept the marriage". Hence, the marriage contract is established between the two parties.
Remarks about the translation
You may find the translation a bit longer than the original but I tried to make it as clear and formal as possible. B.T: though some people tend to marry this way, Such marriage contract isn't valid.
What is a temporal marriage?
I'm not sure that any english person would be familiar with such a term. So having written "timed period" would probably be understandable more than the term "Temporal marriage".