How long did we hate the Germans after WWII? My mother, of German ancestry, married my father, of English ancestry, in 1953. My mother wasn't accepted into my father's family for at least 10 years.
That might have more to do with then-prevailing Anglo-American prejudices than overall American sentiments. They weren't very friendly to the Irish either.
I've been married for 35 years and I have never been accepted into my wife's family. I am Irish.
They are all Demoncrats.