Carlie Gallo sits in a darkened concert balcony, her face illuminated by the light of her BlackBerry.
She’s waiting with her sister and friend for the singer Lily Allen to take the stage, but the 22-year-old’s thumbs are flying as she sends text updates to her boyfriend.
“I made him switch to my network,” she says.
This Valentine’s Day, it’s a good bet that many a love note will arrive by text message, the latest technological tool of the lovesick.
Lisa Tolin is a journalist and Special Projects Editor at NBC News.