The human authors of the Genesis myth told the story to describe their own human experience. In their experience, humans came as male and female. And that's how 'families' were formed and babies were born. so God was the source of that sexual division and propagation by intercourse.

But it is harder to argue that 'God joined' every individual partnership and chose 'this Jane' for 'this Tarzan'. Individual couples are a human choice and 'what man (and woman)' hath joined together. Logically, what humans join together, humans ought to be able to separate.

Plus, that current translation of  " (unless the marriage is unlawful) " is a new version to make it fit our 'doctrine'. The old translations used to say 'unless there is adultery' - and that got changed to 'unless there is 'porneia' - or something like that, which would seem to allow for divorce in cases of infidelity.

Either way, we do love to make Jesus say what we want him to say.