Six Purposes of Marriage

Companionship

True  companionship grows out of a oneness of spirit.  "Can two walk together, except they be agreed?"  Amos 3:3

Enjoyment

The principle behind enjoyment is self-control.  "Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge.  Hebrews 13:4

Completeness

God designed Eve to complete that which was lacking in Adam's life.  "And Adam said.......she shall be called Woman, because she was taken out of Man: 

Fruitfulness

God's first command in Scripture is,  Be fruitful {Hebrew parah, make increase after your kind} and multiply {Hebrew rabah, increase with exceeding abundance of children} and replenish the earth {Hebrew male, fill up the world to overflowing}...Genesis 1:28

The command was repeated in Genesis 9:1 and explained in I Peter 3:7......."as being heirs together of the grace of life; that your prayers be not hindered."

Protection

The husband is to protect the wife by laying down his life for her.  Iphesians 5:25.  The wife is to protect the home as in Titus 2:4-5.  Parents are to protect their children and  to raise up a Godly seed.  Malachi 2:15; Psalm 112:1-2

Typify Christ and the Church

Marriage is to be a human object lesson of the divine relationship between Christ and believers.  Ephesians 5:31-33