Matthew 19:5

For this cause. This quotation, from Gen. 2:24, is almost identical with the text of the LXX. In Genesis the words here quoted appear to be Adam’s statement at the time Eve became his wife, but Jesus specifically assigns to God the statement here cited.

Leave father and mother. During childhood and youth a person’s primary responsibility is to his father and mother. This responsibility continues throughout life (see on Mark 7:11). However, notwithstanding the importance of this obligation it is subordinate to the marriage law, and where the two may come into conflict — as the result of human weaknesses and mistakes — a man’s first responsibility is to his wife.

One flesh. The more a man and woman have in common even before marriage, the greater likelihood that they have will find the companionship marriage should bring and that the union will be a complete success. Conversely, where there are great differences in background, training, attitudes, principles, likes, and dislikes, it is far more difficult to be “one” in mind and spirit, and thus to find success in the marriage relationship.