You seem to have good knowledge of the classical world. What are some of the factors that preceded and contributed to the collapse of the Greek and Roman Empires? Do you see any paralells in contemporary society?
Open homosexuality, collapse of marriage, lack of procreation among the upper classes and a great many other factors are common to classical society and today. These are often mentioned by conservatives to illustrate "why" Rome fell.
Unfortunately, these factors were generally most extreme during the period when these civilizations were at their height of power. They were much less common during the "decline and fall" period, which I thinks blows a pretty good hole in the "homosexuality caused Rome to fall" theory.
After all, Rome was a Christian state for almost two hundred years before it fell.
Anyway, when you actually study ancient attitudes towards these things, they were so dramatically different from any held today by anybody that there is little parallel. Liberals generally view ancient society in a way that is even less realistic than conservatives, as one in which sexuality was free of the guilt imposed by Christianity.
If anything, ancient Greeks and Romans were even more conflicted about sex than people of today. They just had very different types of conflicts, ones that have no parallel at all today.