Genesis 2:24

Therefore a man shall leave, and be separate from the house of the bed of his father and of his mother, and shall consociate with his wife, and both of them shall be one flesh.

THEREFORE SHALL A MAN LEAVE HIS FATHER AND HIS MOTHER, AND SHALL CLEAVE TO HIS WIFE. The Divine Spirit says this, thus prohibiting immoral relationships to “the sons of Noah.”

AND THEY SHALL BE ONE FLESH. The child is created by both parents, and there in the child, their flesh is united into one. Thus the words of Rashi. But there is no point to this since in beast and cattle too, their flesh is united into one in their offspring.
The correct interpretation appears to me to be that in cattle and beast the males have no attachment to their females. Rather, the male mates with any female he finds, and then they go their separate ways. It is for this reason that Scripture states that because the female of man was bone of his bones and flesh of his flesh, he therefore cleaves to her and she nestles in his bosom as his own flesh, and he desires to be with her always. And just as it was with Adam, so was his nature transmitted to his offspring, that the males among them should cleave to their women, leaving their fathers and their mothers, and considering their wives as if they are one flesh with them. A similar sense is found in the verses: For he is our brother, our flesh; to any that is near of his flesh. Those who are close members of the family are called sh’eir basar (near of flesh). Thus man will leave “the flesh” of his father and his mother and their kin and will see that his wife is nearer to him than they.

על כן, seeing that on this first occasion G’d had aimed to make Adam’s wife as much part of him as possible, so that he even used Adam’s personal body as Chavah’s basic skeleton,

יעזוב איש את אביו ואת אמו ודבק באשתו, it is appropriate that a man leave the home of his parents in order to acquire a wife who is compatible with him, and who is a suitable mate for him to live with on a permanent basis. The Torah teaches here also that the expression דיבוק, “cleaving,” being in a state of true union, is not possible between two people who are not alike in their common purpose in life. Parents and children do not have the same tasks and challenges. Man and his wife do have to master the same challenges, hence the word “union” can be applied to their union, whereas the same word would be inappropriate for describing the relationship between father and son, or mother and son. By living together they will become of one mind on how to deal with their lives’ challenges.

והיו לבשר אחד, they are to work together in such close union as if there were in fact only one of them. (This had been the idea behind creating man as both male and female in the first place.)

על כן יעזב איש, some commentators believe that these words were spoken by Moses, not by Adam. The correct interpretation is that they were spoken by Adam, seeing that he was aware that he would father children, for this was why he had been created, in order to populate earth and ensure that his species would be perpetuated on earth, just as all the other species of living creatures. The plain meaning of our verse is close to the words of Targum Onkelos: על כן ישבוק גבר בית משכבי אבוהי ואמיה, “for this purpose a man will leave the house of his father and mother, etc.” The point of all this is that the Torah did not give permission for man to leave, move away from his parents, in order to devote himself to his wife instead, but in order to fulfill the commandment to found his own family, have children. Man is supposed to live in a separate dwelling, separate from that of his parents, in order to have and raise his children.