I don't think Putin actually did say they wouldn't invade, he said it depends on the response of NATO on agreeing to their terms, which were that Ukraine mustn't join NATO and that we should station fewer troops in Eastern Europe. Apparently hundreds of thousands of men had to die with the eventual result that Ukraine won't join NATO anyway because it would mean a war between NATO and Russia, which no sane Western leader wants. So basically we may as well have agreed to their terms because the end result has just been much worse. We called Putins bluff and now we're stuck in this sunk cost fallacy, refusing to negotiate and agree to the original terms, which aren't even unreasonable historically by the way (compared to say the US pulling missiles out of Turkey after the Cuban missile crisis), just to save face. What is funny is that Zelensky originally was angry at the West for telling people Russia was going to invade because the idea was damaging to Ukraine.