Petain was committed to the Armistice, until in the winter of 1940-41 it was clear the nazi government was not going to negotiate a peace treaty anytime soon. The Armistice & Petain were very popular in 1940 as the French universally expected a peace treaty to be completed & 1941 & the end of the occupation. The first significant wave of disillusionment came during the winter when the French had to accept the occupation was going to drag out indefinitely. Close on the heels of that was the Japanese occupation of French Indo China. One of the core rational of the Armistice was the preservation of the empire. The German agreement/encouragment of the Japanese occupation was in direct violation of the Armistice terms. This was a stark reminder the nazis could not be trusted with any agreement.
That also signaled the failure of the 'neutralists' within Petains government. Aside from seeing FIC being slowly hijacked, expectations like the return of the PoW, a halt to looting French industry, withdrawal of the Gestapo, ect... were crushed. This led to the Collaborationists like Laval taking over, which alienated the Germanophobes.
The attack on the USSR in June 1941 was redundant proof of nazi untrustworthiness, and it lost the support of the French left for any sort of neutrality policy. At this point between the leftists and those who hated Germans Petains government had lost the effective support of near half the French population. Petain remained personally popular, but his policies were bankrupt and and ability to effective lead the French population declining. This situation continued through 1942, with morale of the citizenry slowly sinking. The invasion of North Africa by the Allies was the final blow. Petain failed to resist effectively the Allies, which the French facists & Germanophiles, anti English, and imperialists hated. He also failed to effectively resist the Germans and Italians. Which further disillusioned the pro Allied, the leftists, those who despised Germany, ect... When the dust settled the French army had ceased to exist in France, the police lost their independence, the Gestapo and Axis armies has set up shop eliminating the Unoccupied Zone. Petain remained popular with many, but they also recognized he had become a powerless old man who was still allowed to make speeches. As the winter of 1943 spun out the French resistance surged & became more than a marginal or incidental factor for the German occupation.