I'm not sure how much of it is just terminology and how much is an actual difference, but I've found that many (unmarried) couples are still considered "dating" after a few years, whereas here in Europe (e.g. Germany) you would just be considered "a couple" or "together". In my relationship, I only went on a couple of "date" dates in the very beginning. I wouldn't say I'm "dating" my girlfriend although we do occasionally do classical couple activities like going for a nice dinner etc..