"They became man and wife" is a common idiom meaning the same thing. It should be accepted.
indeed, but seems like duolingo supposes that wife=husband and not wife=man.
really? not at any wedding i've been to in the last twenty years. US midwest. it might be true in idaho or north dakota, but i doubt even there.
agree with sternfammenden - man and wife is a common expression (let's not even go into the discussion about whether it sounds like the wife is property - its just a common expression!)
it's not. you won't hear it at any wedding unless they intend to be insulting. ask any minister, priest or judge.
I am in UK. I would say Man and Wife, even though that is not the wording used in the marriage ceremony. It's just a common turn of phrase. It should be accepted.