The pair are in a bit of a money pinch at the moment and have been refusing offers of help for months.
When Person B's birthday comes around, Person A feels horrible about not being able to buy even flowers for them.
With a bit of shame, they swallow their pride and post a message on Facebook(blocked to Person B of course) that asks if someone would mind sending a some flowers or a card to Person B for their birthday because they can't.
They come home late on Person B's birthday with a little cupcake for them. Only to find them waiting, knee deep in vases and bouquets of flowers.
Person A sheepishly tries to explain what they did but they're cut off by Person B tucking a flower behind their ear and kissing them.
They spend the rest of the night pressing flowers and making them into thank you cards.
((And half way through they discover Person B is highly allergic to a flower and they don't know which one.))