I really don't know. Certainly there's room for random variation, but I think you're thinking of a wider trend.
"the arc of the moral universe is long, but it bends toward justice"
things oscillate around some mean, so if the times seem more moral than average, expect regression
In physics, you'd be concerned with how the second derivative (with respect to time) depends on the current state of things. If a lot of acceptance makes people wish to see less acceptance, it's an oscillation. If acceptance breeds more acceptance, it's an upward arc.
I really can't profess to understand humans and sexuality very well. History has shown a good deal of lack of acceptance, at least by the conquering forces that tended toward dominance. But overall, not much data to go on.