What does it mean to be One Flesh in Marriage?

Genesis 2:24 says: Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.

To “become one flesh” means that when a man and a woman get married, the married couple are no longer two entities / individuals, but they have become one single and united body.
So a married couple consists of two people who have become a single entity as a result of the marriage covenant.

To become one flesh means that financially, spiritually, emotionally and in relation to goals and objectives, the husband and wife have become one unit in how they practically live in their marriage.
Within a marriage, the principle of one flesh means that a spouse can no longer make claims of “my money”, “my life”, “my goals”, “my possessions”, “my children”, “my success”.
Instead the correct attitude of a spouse should be “our money”, “our life’, “our goals”, “our possessions”, “our children”, “our success”.

Therefore becoming one flesh is about promoting the principle of sharing and expressing sacrificial love where you love your spouse just as you love yourself.

One flesh in marriage is a reminder of what God did in the beginning of creation.
Adam was created first. God then said “It is not good that the man should be alone; I will make him a helper fit for him.” (Genesis 2:18). 

Genesis 2:21-24 says: So the Lord God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh. 22 And the rib that the Lord God had taken from the man he made into a woman and brought her to the man. 23 Then the man said, “This at last is bone of my bones and flesh of my flesh; she shall be called Woman, because she was taken out of Man.” 24  Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.

So in the beginning God Himself created and instituted marriage to be a union between a man and a woman.
In a Biblical marriage, it is only a male and a female who can become one flesh. Since the beginning of creation and later reaffirmed by Jesus Christ, marriage is solely between 2 genders: male and female.

In Mark 10:6-9 Jesus says: “But from the beginning of the creation, God ‘made them male and female.’ 7 ‘For this reason a man shall leave his father and mother and be joined to his wife, 8 and the two shall become one flesh’; so then they are no longer two, but one flesh. 9 Therefore what God has joined together, let not man separate.”

Becoming one flesh also has a physical aspect in relation to sexual relations between a husband and wife. Sex within marriage is meant for both pleasure and procreation. Adultery is forbidden. Within your marriage, your bodies belong to one another. Therefore sex is meant to continuously cement the oneness between a husband and wife.

1 Corinthians 7:3-5 reads: The husband should give to his wife her conjugal rights, and likewise the wife to her husband. 4 For the wife does not have authority over her own body, but the husband does. Likewise the husband does not have authority over his own body, but the wife does. 5  Do not deprive one another, except perhaps by agreement for a limited time, that you may devote yourselves to prayer; but then come together again, so that Satan may not tempt you because of your lack of self-control.

Conclusion

The principle of a becoming one flesh is Biblical and beneficial because when a couple is united as one, then the marriage is built on a solid foundation.

The principle of one flesh in a marriage creates a healthy marriage in which both husband and wife work together to ensure the success of their relationship no matter the circumstances.