My husband added me on Facebook as we had 28 mutual friends and he thought we must know each other - we didn't! I thought: he's cute, damn he has a girlfriend, oh well.
Two years later we both went to a friend's gig and he introduced himself. He offered to buy me a drink but I thought he still had a girlfriend so I said no and bought my own.
I then discovered he broke up with his gf months before! But he was intrigued by me playing it cool. He messaged me, we arranged to meet and the rest is history.