Yeah, definitely it's the reason.

I can see a few places where it might be awkward, if there are people who feel uncomfortable when she says "pants" or "fanny pack", if she asks him not to say he needs a pack of fags or call people a twat (which is rude in the UK, but not as rude as it is in the US), or if she gets frustrated if she asks for chips and gets the wrong thing, or if they have sports wars over the meaning of football. But ffs sidewalk or elevator or "study for exams" or "third grade" or "soccer" are all words Brits understand.