Of the Shame Which Attends All Sexual Intercourse. Augustine never married. He had a concubine that he loved, and had to give up for his engagement, and another while waiting for his fiancee to come of age. He eventually broke off the engagement and sent away the other concubine. I wonder if that may have skewed his description of sex. "This right action seeks the light, in so far as it seeks to be known, but yet dreads being seen. And why so, if not because that which is by nature fitting and decent is so done as to be accompanied with a shame-begetting penalty of sin?"
I think he suffered a failure of the imagination here--perhaps he should have asked some married friends about the matter. Wanting Privacy ≠ Shame. For that matter, Embarrassment ≠ Shame. Even something as simple as writing poetry suffers tremendously when other people hang around--in fact it can feel embarrassing for others to see it "half-done" and "in process."
Of course there can be plenty of reason for shame if those involved are not entitled to be involved, or are indulging cruelty or vice. But the basic marital act is a husband and wife giving themselves to each other, not to kibitzers.