For this reason a man shall leave his father and his mother, and be joined to his wife; and they shall become one flesh.
Genesis 2:24 (NASB)
One of the times a bible character actually does “leave his mother and father to be joined to his wife," per the note in Genesis 2, is with the story of Jacob… where he fled home to avoid his brother's wrath, and then ended up marrying two women – Leah and Rachel.
But the first time we see it followed, it's here with Cain. It makes me wonder if this is a blessing or a curse.
Then Cain left the presence of the Lord, and settled in the land of Nod, east of Eden.
Cain had relations with his wife and she conceived, and gave birth to Enoch; and Cain built a city, and named the city Enoch, after the name of his son.
Genesis 4:16-17 (NASB)