Zelenskiy's #1 campaign promise was to negotiate peace with Russia - meaning fulfilling Ukraine's part of the Minsk accords, perhaps with some concessions. Overall, about 65% of the votes went to parties supporting it. ~72% if Donbas is included. There was a clear democratic mandate to do it

To his credit, he did try to set things in motion. Mere days after, ultra-nationalist right-wing militias threw violent protests, in which they tossed grenades at police, killing three, calling Zelenskiy a traitor and threatening to take his life if peace is enacted. The peace negotiator was arrested for treason. Zelenskiy backed down, reneged on his #1 campaign promise, and started ramping up the tensions. As a result, the polling results for his party dropped from ~50% to mere 17% at the onset of the war. We don't know what happened behind the doors to cause such a 180 turn, but it sure wasn't pretty