There has probably been a language gap, right? Or was it common back then to be bilingual (similarly to today) simply because one's life had greater potential from knowing the language of those living so closely.
Were marriages between French and German locals common?
Was there some sort of animosity between them or were they on friendly terms?
I don't know how strictly borders were perceived in the Middle Ages, nor do I know whether international (as it were) marriages were common. But as for your question about languages, numerous dialects were spoken in France and Germany; those who travelled to different regions (e.g., merchants) would be competent in other dialects as necessitated by their profession.. Any language barrier that existed between nearby towns in France and Germany would have been less than a language gap between that same French town and one in Gascony. Map of different languages of Medieval France.
But I think the broader questions you're (implicitly) asking about national/linguistic pride or identity are interesting, so I hope someone can answer!
