No they never ‘fled in disgrace’ that was Russia in Afghanistan, actually losing some of the battles. In both Vietnam and Afghanistan the US won the initial battles decisively, but eventually decided its terrorist and partisan losses were unacceptable.. But predictably Biden rushed the Afghanistan withdrawal for political reasons and bungled the whole thing.
Russia had a relevant ground force in WW2 when tanks ruled the battlefield and numbers dominated. With modern technological warfare those advantages are gone and even in WW2 smart analysts point to German weakness, particularly in fuel, rather than Russian strength.
Hell Japan defeated Russia in the 20th century setting up yet another precondition for the disastrous revolution which has negated Russia’s progress in the modern world.
Who knows what the EU will ultimately do….but if Ukraine is abandoned Europe is going to look a lot less desirable, especially as that will suggest a U.S. withdrawal of interest. The economic consequences of that will be far greater than the needed Ukraine support.
As for the patience argument….please. Russia walked into the Ukraine as a big screw you to the West. You don’t make a power statement like that and then get fought to a standstill by a much smaller military if you can avoid it.
Russia set out to take Kiev and was stopped by anti tank technology. They are doing everything they can to win the war. That just turns out to be not enough.