We must get together sometime
What it really means
A warm-sounding phrase that is often just a polite way to end a conversation, not a real plan. If no date is suggested, it may never happen. A real invitation usually includes a specific time.
Context, tips & common mistakes
"We must get together sometime" — like "we should do this more often" and "let's grab a coffee at some point" — expresses warmth, not scheduling. It is the conversational equivalent of a wave: the correct reply is equal warmth ("yes, definitely!") with no diary consulted, and neither party is lying, because the sentence was never an offer.
The useful trick is conversion: if you would actually like to meet, answer the ritual with a concrete proposal — "I'd love that; how's next Thursday?" A Brit who meant it will engage with the date; one who did not will produce a vaguer deferral, and you have your answer either way, gracefully. Newcomers who learn to tell ritual warmth from real invitations save themselves months of quiet confusion about British friendliness.