politics

Although all of this is basically true, the fascist slaughter of people in Donbass wasn't even the deciding factor. Whether Ukraine was accepting NATO weaponry, military infrastructure, training exercises, and hopeful, near-future membership was. Russia wouldn't have invaded even to stop the potential genocide going on. It invaded because the U.S. was threatening its western border and escalating the Cold War (again/still). It's exactly as if Russia had made an agreement with Mexico to put military bases and weapon systems right on the U.S.'s southern border. (Or maybe Canada would be a better parallel, due to the proximity the weapons systems would then have to Washington DC.)

So it WAS avoidable. Just on a slightly different basis than whether or not Ukrofascists were happily doing their thing unmolested (which they also were).