Macron is president actually, not PM (unlike most European parliamentary republics, the French president is more than a mere figurehead, similar in that regard to the POTUS on your side of the pond. As for the PM, they're usually little more than the president's mouthpiece, unless the latter happens to lose his parliamentary majority, in which case he's forced to cohabit with an opposition PM, who becomes the main decision-maker for domestic policy, while the president has to content himself with matters of foreign policy — such a scenario happened three times in the history of the Fifth Republic: twice under Mitterrand in 1986 and 1993, and once under Chirac in 1997).
Now the Borne government is facing several votes of no-confidence come Monday, one of which is being pushed by a dissident centrist group and has the best chances of transpartisan support (from the left-wing NUPES, the far-right RN and members of LR who are ready to defy the voting instructions of their party's higher-ups, if only out of fear of becoming themselves the targets of the current popular discontent).
Should it fail or Macron decide to disregard it, it'll only fan the flames in the streets.
Macron really shouldn't have banked on the French people having somehow become complacent since the pandemic (which had forced him to provisionally shelve that reform): if there's something they absolutely hate to see the government mess with, it's their retirement plans.