Translation
On this ground
Go to footnote numbera man
Go to footnote numberleaves behind
Go to footnote numberhis father and mother and clings
Go to footnote numberto his wife,
Go to footnote numberand they become one body. (See comment below.)
Paraphrase
Based on the pattern that was established back then, a man moves out from under the direct authority of his father and mother and becomes closely united to his wife and they become one family and one body [when their love produces their first child.] (See comment below.)
Footnotes
1: “on this ground”
This verse contains principles that appear to have been added later by someone else such as Moses when he wrote down the oral tradition that had been handed down from generation to generation.
The phrase used here basically means “on this ground,” and it fulfills the role of our English phrases “based on this, or on account of this.”
What is based on what? The leaving to establish a new household is based on the fact that God provided a companion that was perfectly suited for man; the closeness of their relationship was based on the way the woman was taken out of man, one became two, and now two would become one again.
2
Once again this is not “the adam,” but the other word for “man.”
3: "Leaves behind”
When a man and woman get married, the relationship they establish replaces the relationship of parent to child as the new priority of top importance. Because it is now the most important relationship it requires both man and woman to leave their parents, otherwise there may be a confusion of the authority structure. Dad may want to continue exercising the level of authority he always has, or something close to it, therefore the new couple must leave to establish their own family unit with their own authority structures.
4
This word means “to cling to, to stick to” as the tongue sticks to the roof of your mouth when you are desperately thirsty. “Clinging and sticking” bring with them a picture of great closeness, thus it becomes a picture of the closeness desired from a marriage relationship. There is also a hint in this verse that loyalty and continued closeness are expected.”
5: “his wife”
This is simply the word for “woman,” the word that sounds like the word for man and emphasizes the fact that she was taken out of man. Context in cases like this tells that it is a woman who is in a special relationship with a man, thus a wife.
Various Levels of Meaning for "one body"
The word I have rendered in the translation as “body” can also mean “flesh” (i.e. tissue, or part of a body) or “family,” i.e. blood relatives. I have chosen “body” because I feel it encapsulates the total package best, the physical body and the family.
But there is a problem here. We all know that a man and woman cannot become one indivisible mass of tissue or cease to be two bodies and become one single unified body. Or can they? What is a baby after all? It is a unified, indivisible, well organized mass of tissues and organs taken partially from him and partially from her, 23 chromosomes from each parent. This union of the DNA from two different people is a miracle, a seeming impossibility. It is truly the joining of two people into one person, a little person, unique from them, but coming jointly from each of them. By translating it “they become one body” I have tried to highlight the fact that it does actually come true, but that part of the perfect union is not fulfilled until the first child is conceived.
The word “flesh” can also mean family. Even in English we talk about “my flesh and blood.” So the new couple also becomes a new family unit, distinct from his parents and from her parents. They will establish their own micro-culture within the walls of their home. It is unique, it is one, it is not two.
There is also a unity, a oneness that comes from a close relationship. The type of unity described here requires that a husband and wife be pursuing the same purpose in life and act selflessly toward each other, putting the other one before themselves. These two words, “one body,” are an entire description of what a healthy marriage should look like; they carry with them relational, spiritual, sexual, financial, and child-rearing implications.