Genesis 2:24

Therefore shall a man leave his father and his mother and shall cleave unto his wife; and they shall be one flesh. Whether Adam spoke these words, or whether Moses wrote them in explanation of this wonderful relation which was to obtain between the man and the woman made to be his helpmeet, it was God that inspired them, Matthew 19:5. When, in the manner approved by God, a man has been given the woman whom God has destined for him, then the tie which binds these two together is so close and so indissoluble that the man will sever the former intimate ties of home and be joined with his wife as her husband, under obligation to observe all the duties that this relationship implies, Ephesians 5:29, even as the wife will be guided in her entire life by God's will, 1 Corinthians 11:8, as the helpmeet of the man. Man and wife are supposed to be united by the ties of common interests, sharing weal and woes, joy and sorrow, as though they were one single person. Note that this excludes the idea of polygamy.