If someone asks me for “a few” I’ll give them three or four. If someone asks for “multiple” I’ll give them a handful and ask if that’s enough.

I don’t know where in the world this theory is coming from, but here, two would be “a couple” and three+ would be “a few.” Not that “a pair” (never just pair) and multiple aren’t used in other contexts, but you wouldn’t use pair and multiple in the same context. A pair is specific, multiple is an estimate.