I am in no doubt that the sole purpose of sexual relations is procreation. This is what God intended.
Genesis
1Now the serpent was more subtle than any beast of the field which the LORD God had made. And he said unto the woman, "Yea, hath God said, `Ye shall not eat of every tree of the garden'?"
2And the woman said unto the serpent, "We may eat of the fruit of the trees of the garden,
3but of the fruit of the tree which is in the midst of the garden, God hath said, `Ye shall not eat of it, neither shall ye touch it,lest ye die.'"
I don't believe God was referring to literal death here, but rather to a kind of spiritual and moral death
4And the serpent said unto the woman, "Ye shall not surely die;
5for God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil."
Meaning, she will no longer interpret the world in innocence and naivety as God intended, but will be unable to look upon a naked form (in this case Adam's) without her mind rapidly descending into the gutter
6And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof and ate, and gave also unto her husband with her; and he ate.
7And the eyes of them both were opened, and they knew that they were naked; and they sewed fig leaves together, and made themselves things to gird about.
Obviously, they must have noticed they were naked before, but placed no significance upon it. However, having eaten of the Forbidden Fruit, they now looked upon one another and were no longer confronted with the impression of naked innocence, but rather something of a shamefully salacious and distasteful significance. No doubt Adam would have been shocked to find himself standing to before Eve's wanton display, and with dreadful embarrasment, quickly rushed to cover themselves up. It was at this precise point, that the possibility of sexual relations for any purpose other than procreation came into being, as a direct consequence of Eve not doing as she was told.
God was clearly so angry about this, he banished them from the Garden of Eden and placed a burden upon them evermore.
So, it is clear to me, that if we are to earn the approval of our Lord, we must aspire to be like Adam and Eve before the Serpent tempted them toward sin. Enjoying intimate union for its own sake draws a very clear parallel with Eve's original sin, and if it couldn't be tolerated then, it certainly shouldn't be tolerated now.