Zelensky should have listened to Donbas separatists and met to address them (Minsk agreements)
Russia should have listened to the Ukrainian democratically elected government and met to address them
And yes, NATO should have listened to Putin and other Russian officials saying over and for years about the bright lines, and should have listened to internal voices including the architects of the USSR containment strategy WARNING about NATO expansion, and realized they should invite Russia into NATO.
No one listens because of the apparatus within their country, and the idea that cities do not have self-determination, only countries do. People believe in their flag so much because of mass media and government schools, they are willing to kill and be killed for it.
But if you look at a time-lapse of most places on the globe, you’ll see flags changing so quickly that you wonder what is the big deal. Most people if left alone would just earn money and raise their families.