A marriage union between two agreeing partners, witnessed by the friends and community and God is viewed as a marriage in western thinking. In some countries, this also has a legal requirement, a paper to witness to the vows given and received. In Christian marriage this will normally include vows given freely before God and witnesses. It is meant to be life long, it is viewed as a covenant between two parties. The Divine law of marriage is nothing else but the order of nature.
Marriage is an entire union of man and woman.
This is for the sake of the children with both partners acting as guardians to the next generation. He created them. They were to have children and fill the earth. This relationship should be an example to society, helping and comforting, both in prosperity and adversity. This is God's purpose and ideal, however we humans often fail to work this out in practical living and instead of seeking the Lord concerning the marriage relationship, we decide to end our marriage.