They aren’t the “perfect one” because they have a key ring with sixty keys and on the first or second try, find the right one for the door.  In relationships, that might be called “a natural fit”, but if I had my choice, I might rather choose the person who would stand patiently in the dark trying every key on the ring because the truth is, that is the one.  That is who truly loves you.  That is the one that will fight for you.  That is the one that when the chips are down, will stay in the game