Marriage customs are very varied. Your suggestion is quite seriously followed in Iran, because Shia Islam allows the institution of "temporary marriage". This is a union contracted for a specific amount of time, which can be as short as an hour, with both partners agreeing to the duration, and the "gift" paid by the man to the woman. He is free of the obligation to support her (which always applies in a permanent union) but he has to acknowledge paternity of a child, and support it, if she has one. Men can make as many temporary marriages as they want. Women can only have one after a "waiting period" of more than 6 weeks - in order to settle any questions of paternity. Of course, most people in a temporary union do not aim to have children. In Persian slang, it is a "pleasure marriage."
This is specific to Shia Islam, the Sunnis don't have it, and indeed any mention of temporary marriage puts them in a rage. However, it has limited cases of adultery before the Islamic courts in Iran, where such cases are rarer than in Pakistan or Saudi Arabia.
Reader David, I am flagging you to this, because I think that you had commented on this in an earlier thread. You can back up what I am saying! I expect some incredulous reactions. (On the other hand, if it wasn't you, and you have never heard of temporary marriage, I apologise.)