Christine Robinson was looking forward to a date night with her husband, Robert. She grilled flatbread veggie pizza, opened a bottle of Cabernet and lighted some candles.

Her husband took a sip of wine, swished it around in his mouth, then bit off the triangle tip of a pizza slice with a crunch. “The mix between the crispiness of the crust, the chewiness of the toppings and the slurping of the wine is what did it,” Ms. Robinson says.

She...