I don't buy this. You can, for the purposes of your argument, reduce marriage to being something like an economic contract, that's fine; but, in reality, that's not what marriage is/has been primarily about.
Also, solving the burden of work for one sex isn't a solution. Granted, it's better than nothing.
Ancient societies' marriages we have records about were principally about economics and politics.
Maybe the poor were having love marriages. We don't know because most of our sources couldn't be bothered with them. But to the degree we have evidence, it's in even poor landowners preferring to marry children off to the owners of adjoining plots. Like, maybe that's a coïncidence. But probably not.
If anything, political marriages are defined by a marriage outside your economic sphere of influence (which for ancient agricultural workers would generally be about a three day journey due to the ox problem), and to someone you don't know. These couples probably grew up together and went to social events like church together from birth.