According to one teaching of the Buddha, a couple was very much in love with each other. They asked the Buddha what the should do so that their relationship would last all of this life and in future lives. The Buddha told them about the Four Relationship Qualities that have to be matched so that a positive relationship can come about for now and for the future, Wisdom, Generosity, Morality and Faith/Confidence.
Steve and I "knew" each other when we first met. How it happened I don't know but our qualities seemed to be matched. Probably we have been practicing these qualities together in past lives. Sometimes you meet somebody and very often, for me at least, it is like I know them, I recognize them. So often there is a connection that we can't explain. How can we recognize each other? I don't know. There are some people who have love on first sight, as Steve and I did.