In Matt. 19:4 we are told by Jesus that God created one “male and [one] female” and joined them in marriage. Mark 10:6-8:"But from the beginning of the creation, God 'made them male and female.' 'For this reason a man shall leave his father and mother and be joined to his wife, 'and the two shall become one flesh'; so then they are no longer two, but one flesh.
The two as one is the pattern on how marriage was to be conducted from the start. NOT three or four as one.