Ukrainians were/are still fighting to defend themselves from an illegal invasion. But America sees and has always seen Ukraine as a proxy to weaken a geo-strategic rival. NATO was not realistically on the table as long as the conflict in the Donbas was ongoing (it would have immediately triggered art.5) to keep promising NATO instead of working on a more realistic path to peace has probably caused the death of 100000s of Ukrainians. And just as with many other imperial proxies in history, the proxy is left to deal with the fallout while the empire retreats to the metropol and prepares for the next conflict.