Perhaps the most egregious divergence between perception and reality of 1968 stemmed from the Tet Offensive. In reality, although the Viet Cong had attacked (during a cease fire) every provincial capital in South Vietnam in a coordinated attack, they were repulsed, with major losses.
After that, almost every major engagement in the war was against North Vietnamese Regular troops, and not the 'black pajama' clad irregular troops. The peasant uprising that Marxism assured failed to appear.
This was a very significant development in the progress of the war, for despite still having the tunnel complexes (some dating back to French Colonialism in Indochina), the NVA no longer had the substantial cadres of guerilla fighters it had possessed prior to Tet. They'd been hurt, militarily.
However, with full gravitas, the talking heads on television (especially, but not exclusively Cronkite) presented this military victory as a sign of defeat or at best a stalemate. In their doing so, the Communists won the propaganda war, despite military defeat on the battlefield.
Once presented as "unwinnable", objection to the war and the draft (much like NYC in 1863) gained serious traction, and civil unrest, especially on college campuses (where many draft age young men were) expanded.
So, too did the ranks of college students, some of whom were there on the GI Bill, while others sought draft deferments.
Arm in arm with that was the racial unrest, especially after Martin Luther King Jr.'s assassination, and street riots and looting (always with the looting) became more commonplace. Among those throngs, however were the media, always willing to edit the tape and present yet another instance of police brutality (because outrage sells papers and brought viewers). It didn't have to be real. A real, vicious criminal might be executed on the streets of Saigon, but if captured on film, the harshness of that execution (by western standards) was exploited for political talking points. If we recall, though, the people now against the war were from the same political party that took our involvement from a few advisors to full blown warfare, but were now framing their reinvented selves as being for Peace. (Even more ironically, the disengagement from that conflict was orchestrated by the opposite Party, even as they were framed in the media and the public psyche as being 'war mongers'.
There we see a few things going on: Communism was making inroads into the Democrat Party, not at the top, but at the street level.
The Media were discovering the very real power they had in shaping narratives, especially with video clips, and not just distortions in prose.
Socially, the Pill had come on the scene in midst of the spirit of revolution, and the standards for social behaviour shifted, away from more traditional mores to a more openly libertine culture, reflected in entertainment media and print.
So the slide was across a spectrum of behaviour, and even country music took up the standard of sexual freedom in a song about The Pill.
The most amazing part to me, was that media distortion was at the root of much of this, poking here, prodding there, fanning the flames on one hand and quietly undermining faith on the other. Through all the cultural upheaval, somehow people kept trusting the forked tongues and talking heads, as the Fourth Estate became the Fifth Column in America.