"You are now a husband and a wife."
Translation:Te olette nyt mies ja vaimo.
You don't use the article before "husband" either. It's an idiomatic expression that is most likely a left-over from the Germanic roots of English, from back when articles weren't used about people being something, just like in modern day German and Swedish. The inclusion of the articles implies that they are not necessarily married to each other, while using the idiomatic expression correctly by having no articles would make it clear that they are each other's spouses.