ご adds politeness to 馳走 (“a feast or treat”), さま adds respect, and でした puts the thanks after the event.
ご adds politeness to 馳走 (“a feast or treat”), さま adds respect, and でした puts the thanks after the event.
When do you say ごちそうさまでした?
After finishing a meal, or later when thanking someone who treated you.
Who says it?
The person who ate the meal.
What do you say before eating?
いただきます is said before the meal.
Can you say it at a restaurant?
Yes, often as you leave or pay.
Why say it about a couple?
It playfully treats their affectionate story as a full meal.