Create a 4K portrait of a thin, not mid weighed, couple s...

Create a 4K portrait of a thin, not mid weighed, couple sitting in a 1950s diner, sharing a milkshake. The couple should be wearing 1950s fashion clothing. The setting should feature pastel-colored booths and neon signs in the background. The photo should have soft light, a slight grain, and a pastel color palette to evoke the innocence and charm of mid-century romance.