Portuguese and Germans are different races? Okayyy...
Molly: "You're a racist"
Warlord: "No, I'm not. Proof: I'm dating Portuguese girl."
Counterquestion: What race (again, I am not the one bringing race into this) is it that in this very case Germans and Portuguese belong to?
Germans, Frenchs, Portuguese, Italians, Brits, Poles and so on all have different languages, culture, conventions and traditions, but still we all share a common history, the same religion (at least in the very core) and most importantly the Enlightenment, which resulted in the free democratic basic order all european countries (more or less at least) have.
That is why Germans, Frenchs, Portuguese, Italians, Brits, Poles and so on can live together peacefully and
mostly without trouble. It really isn't some kind of magic, it is pretty much common sense.