21.
“I once had a boyfriend who was embarrassed by me at every turn. And once when we were shopping, I heard a song on the store radio that I liked so I did a little foxtrot down the aisle. Well, when I turned around, my boyfriend was gone. I looked for him for 30 minutes, and then I went outside to see that the car was gone too! That jerk had just left me at the grocery store and wouldn’t even answer the phone when I called…
“Well, later, I was dating a new guy and we happened to be at the exact same store when the exact same song came on, and I resisted the urge to dance. But to my delighted surprise, my new guy swept me up into his arms and danced with me. That’s when I knew he was the one. And 15 years later, we still dance in the store together.”
—lachlanfox
Source: https://www.buzzfeed.com/asiawmclain/how-people-knew-they-found-the-one