I work at a university, where I encounter lots of young students every day.
Sometimes, as I did just now, I encounter a young would-be couple flirting with each other.
She is all dressed up today. He asks her a question. She blushes and giggles. He leans a little closer, ever so slightly, and tries to say something witty. They don't even notice me walking by. Then they part - in 30 seconds, they've made each other's day.
I love witnessing these encounters. They remind me of our early dating days and all those lovely feelings.