They become one flesh in a child. It's basic biology. That's the union.
Again, You are not the arbiter of how Scripture should be interpreted, Scripture is, and the Hebrew in Genesis 2:24 is explicitly defining the union of a man and woman in the
covenant of marriage, and that the two become '
one flesh'
Your response is not Biblical and completely
unacceptable!
Apparently, you need the greater context for clarification,
Genesis 2:18-24
18 Then the LORD God said, "It is not good for the man to be alone; I will make him a helper suitable for him."
19 Out of the ground the LORD God formed every beast of the field and every bird of the sky, and brought
them to the man to see what he would call them; and whatever the man called a living creature, that was its name.
20 The man gave names to all the cattle, and to the birds of the sky, and to every beast of the field, but for Adam there was not found a helper suitable for him.
21 So the LORD God caused a deep sleep to fall upon the man, and he slept; then He took one of his ribs and closed up the
flesh at that place.
22 The LORD God fashioned into a woman the rib which He had taken from the man, and brought her to the man.
23 The man said, "This is now bone of my bones, And
flesh of my flesh; She shall be called Woman, Because she was taken out of Man."
24 For this reason a man shall leave his father and his mother, and be joined to his wife; and
they shall become one flesh.
God handed the bride to Adam and God takes serious the supernatural and spiritual union of the marriage covenant, (Malachi 2:13-16)
'
Echad' definitely illustrates a plurality within a singular entity, oneness but not sameness, unity and diversity
Furthermore, God's statement here is representative of all humanity, and down through the ages there have been a great multitude of God fearing marriages who were never able to have children, which exposes your interpretation and response to be in error!
RCM