Used to show the functionality of "storyboardthat"
Normal, everyday married couple
"They were a couple in their late thirties, and they looked unmistakably married." "There was nothing conspicuous about them, nothing particularly noticeable..."
"It arrived, in the form of a small but glossy birthday cake..."
Shift in emotion
"It became clear at once that help was needed, because the husband was not pleased. Instead, he was hotly embarrassed, and indignant as his wife for embarrassing him."
The narrator simply notes that two people are eating at the restaurant and are a normal, everyday couple. The narrator's focus on their blandness makes the future events that much harsher in contrast. The reader might also assume a married couple is happy, which makes the resolution to the story more upseting.
The narrator notes the coming of the cake. The restaurant patrons and its worker join in to cheer and celebrate the husband's birthday. The use of the words "it arrived" by the narrator indicate that there is something more about to happen than a simple, happy birthday party.
The small shifts in the husband's emotion are noticed by the narrator and communicated to the reader. He was clearly upset and quietly containing his anger with his wife even though she was pleased with her surprise. It's clear that the conflict that arrived with the birthday cake will only progresses from here.