Wendigo and I are each other's secondaries. I met him though my husband and our mutual friends and have always know he was married. Infact the firs time I met him was at the apartment his brother in law was sharing with a mutual friend. We were friends for a couple years before we got together and I saw his wife in passing when we gave him rides to our boffer LARP, but we didn't actually meet and start conversing until Wendigo and I had been dating for a couple of months as she is very much an introvert and going out to dinner once or twice a year is about as social as she gets.
Runic Wolf's last girlfriend he met on OK cupid and she is a member of our local poly community so telling her he was married was easy. She and I still talk occasionally.