"For this reason man will leave his father and mother and will unite with his wife, and they will become one flesh" (Eph 5:31).
Marriage is a divine institution. God instituted marriage for his glory, the happiness of the human being and the perpetuation of the race. This conceptuada institution, not observing its divine origin, has been attacked with excessive rigor, and that, from the most remote times. In light of the text in question, there are three divine precepts about marriage. Consider the following:
First, marriage is heterosexual. "That is why he will leave the man to his father and his mother and will join his wife ...". The wedding has a let and join. Before man joining his wife, he needs to leave father and mother. But the man who leaves father and mother leaves them to join his wife and not another man. Marriage, according to the divine precepts, is not the union between a man and another man or between a woman and another woman. The homoafetive relationship, although, receives the approval of men, does not find God's approval. The divine precepts do not remain squatting in front of human precepts. What society, sick for sin, calls of love, the word of God calls infamous passion. What they say is a success, the word of God calls error. What he says is natural, the word of God says it is unnatural. What they say is a conquest, the word of God says it is awkward (Rm 1.24-28). No human tribunal, however conspicuous, can undo the divine precepts. They are not the human laws that legitimize the word of God, but the word of God that judges all laws. Marriage as instituted by God was, is, and will always be heterosexual. What happens from that is the fruit of the deceptive human heart.
Second, marriage is monogamous. "... will leave the man to his father and his mother and will join his wife." Marriage is the relationship between a man and a woman and not between a man and several women or the union between a woman and several men. Polygeny (the union of a man with several women) and polyandry (the union of a woman with several men) are outside the divine purpose. Although polygamy was common in some cultures, the divine precepts about monogamy are crystal clear. In creation, God made it evident in Genesis 2.24: "Therefore, he leaves man father and mother and joins his wife, making both of them one flesh." In the delivery of the ten commandments, the moral law of God, that same truth was reaffirmed in Exodus 20:17: "... you shall not covet your neighbor's wife ...". In the dispensation of grace, Jesus consolidated that same principle in Matthew 19: 4: "... you have not read that the Creator, from the beginning, made them man and woman and said: For this cause he will leave man father and mother and will join his wife, - the two a single meat? ". It is, then, crystal clear that marriage, besides being heterosexual, is also monogamous!
Third, marriage is monosomic. "... and they will become one flesh." God created man and woman, male and female. God created them with the ability to love and be loved, to feel pleasure and to give pleasure. Sex is pure, holy and delightful. But sex should only be enjoyed in the sacrosanct context of marriage. In marriage, man and woman become one flesh. Sex before marriage is fornication and those who practice it are under divine judgment (1Ts 4.3-8). Sex outside marriage is adultery and only those who want to destroy commit such madness (Pv 6.32). Sex in marriage, however, is a divine ordinance (1Co 7.5).
Sex in marriage is like the waters of a river. When these waters run inside the bed, they bring life and pleasure wherever they go, but when they overflow and leave the bed, they bring destruction wherever they arrive. It is clear, therefore, to affirm: marriage is heterosexual, monogamous and monosomic. What happens to that, does not come from God.