God set the standard for the marriage covenant before there were in-laws. In spite of this fact, he did not overlook the fact that there might be problems with insecurity and dependency. Thus in Gen 2:24 God set the boundaries when He used two important words that we must never overlook or forget: Leave and Cleave.
The Hebrew word in Gen. 2:24 for leave means “to leave” “to let go” or “leave behind.” The Hebrew word for word for cleave means “to cling or adhere,” “to be joined together,” “to stick” like something glued together. The Greek words for leave and cleave in Matt 19:5 and Mark 10:7 have the same meanings.
For the verses to be understood correctly both concepts have to be accepted. It is not a leaving without a cleaving or a cleaving without a leaving. It does not mean that one person in the marriage must leave and cleave while the other only cleaves but does not leave. To leave must include not only location but dependency. Each person in the marriage covenant, husband and wife, must leave their parents and both of them must realize they have been “glued together” by God in a new inseparable bond. To break the bond means to tear up something that God has created and that was meant to have a separate identity.
To leave does not mean “to forsake” in the sense of rejecting love or loyalty but it does mean the “to forsake” in the sense of accepting a marital love that surpasses the familial love. “To Leave” does not mean to turn away from parents in the sense of rejection but in the sense of moving into a new a greater sphere of allegiance.
To leave and to cleave is beautifully pictured in Eph 5:22-31
22 Wives, submit yourselves unto your own husbands, as unto the Lord.
23 For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body.
24 Therefore as the church is subject unto Christ, so let the wives be to their own husbands in every thing.
25 Husbands, love your wives, even as Christ also loved the church, and gave himself for it;
26 That he might sanctify and cleanse it with the washing of water by the word,
27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.
28 So ought men to love their wives as their own bodies. He that loveth his wife loveth himself.
29 For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church:
30 For we are members of his body, of his flesh, and of his bones.
31 For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh. KJV