On Marriage

Marriage is more than just pro-creation; it is complementary. Men and women were created to complete each other, whether they have children or not.
  In the Book of Genesis it says:
The Lord God said: "It is not good for the man to be alone. I will make a suitable partner for him."... So the Lord God cast a deep sleep on the man, and while he was asleep, he took out one of his ribs and closed up its place with flesh. The Lord God then built up into a woman the rib that he had taken from the man. When he brought her to the man, the man said: "This one, at last, is bone of my bones and flesh of my flesh; This one shall be called 'woman,' for out of 'her man' this one has been taken."  That is why a man leaves his father and mother and clings to his wife, and the two of them become one body. (Chapter 2:18-24)
  Although men can be very good friends with men, and women can be very good friends with other women, it's not the same kind of relationship as a man and a woman. And that's how God planned it.  God looked at everything He had made, and He found it very good. Genesis 1:31