Correct me if I'm wrong, but I think a lot of words we use from other nations existed before the English language we use today. So if the concept already existed before the language, we would probably just carry over those terms instead of creating new ones.
That's funny, I feel kinda the same with hearing it in a French discourse above and in an English one in the second panel. The way of pronouncing it with particular emphasis makes it sound really fancy compared to how I'm used to hearing it in French.
It did: 'betrothed.' It's still in use today, though very rarely, since it sounds kinda old-fashioned or pretentious.