Three is a sacred number, and represents among other things, strength. A three braided cord is harder to break than a two braided one. Ecc. 4:12 . As Māori, we see the the strength in whānau, hapu, iwi ( family, subtribe, main tribe). The importance of family, also the construct of a person,as spirit,soul, and body. I am sure you can think of some relevant to you as well. For my wife and I, we are two but what holds us together is seen in a third Person, our faith.