It is, in a nutshell, American weakness.
Americans do not know history or geography. They also believed impeding Hitler was not their fight. They cared about Polish Corridor as much as you care about Donbas now.
You claim you read my article, but you write that Putin “reasonably does not want NATO encroaching so close to Russia, and if you were in his shoes, you wouldn’t either.” Was not I clear in my article that no one in the whole world wants any piece of Russia. Everyone wants to do business with them, but we want to do business with Ukraine too. No one suggested Ukraine should join NATO until it became obvious that Russia wanted to run Ukraine as its colony.