Thank you for sharing the search results from the Fathers, dmar. I read through some of them, and a couple things come to mind: First, a number of the Fathers agree that marriage is a good thing. It isn’t a necessary evil. To me, that would imply that marriage is not a product of the fall. The question of sexual desire is still a bit ambiguous, though. St. John Chrysostom appears to teach that sexual relations in marriage are good in the following quote:
And while thou, fresh from the company of your own wife, darest not pray, although this is no blame at all; do you lift up your hands, fresh from reviling and insult, which brings after it no less than hell, before you have well cleansed yourself? And how do you not shudder? Tell me. Have you not heard Paul, saying, “Marriage is honorable, and the bed undefiled?” [Hebrews 13:4] But if on rising from the undefiled bed, you dare not draw near in prayer, how do you coming from the bed of the devil call on that awful and terrible name? For it is truly the devil’s bed, to wallow in insults and reviling
He’s contrasting sexual relations in marriage with sinful insults and badmouthing. In a nutshell, I think I could paraphrase him as saying “You treat sex with your wife as if it’s dirty and unbecoming of the Lord, but then you go out and insult people. You’ve got it mixed up! Sex in marriage is blameless.”
But then Augustine offers a view that seems more complex in his work “On the Good of Marriage”. First, he affirms that marriage is good:
…marriage and fornication are not two evils, whereof the second is worse: but marriage and continence are two goods, whereof the second is better…
Then, he implies that sexual intercourse can serve to deepen friendship between a husband and wife:
God gives us some goods, which are to be sought for their own sake, such as wisdom, health, friendship: but others, which are necessary for the sake of somewhat, such as learning, meat, drink, sleep, marriage, sexual intercourse. For of these certain are necessary for the sake of wisdom, as learning: certain for the sake of health, as meat and drink and sleep: certain for the sake of friendship, as marriage or sexual intercourse: for hence subsists the propagation of the human kind, wherein friendly fellowship is a great good.
But later on, he suggests that it is a fault for a husband and wife to have relations that are not explicitly necessary for obtaining children:
For necessary sexual intercourse for begetting is free from blame, and itself is alone worthy of marriage. But that which goes beyond this necessity, no longer follows reason, but lust. And yet it pertains to the character of marriage, not to exact this, but to yield it to the partner, lest by fornication the other sin damnably.
These writings are somewhat tangential to the topic of sexual desire. If Augustine believed that sex should ONLY be pursued with the intention of conceiving a child, maybe he believed that sexual desire was a fault?