perhaps i am guilty of double standards (though i try not to) but i DO think it is slightly different when it is your home being invaded vs when you are the ones doing the invading.
All Russia have to do to end the war right now is to stop invading, ukraine on the other hand have no choice other than to fight on with what ever they have (well that or submit to Russian occupation i suppose and accept all the war crimes against them)
Russia doesn't see it like that though, they see it as them helping areas of largely Russian speaking people which were essentially fighting a civil war against the Ukrainian government. Yes, Russia is invading a part of Ukraine, but that part of Ukraine was in a conflict with the Ukrainian government, they were shelling each other and fighting, normally governments don't shell part of their own country. Further complicated by the fact that the Ukrainian government is backed by the EU (mostly benevolent towards Russia to be fair), and US (mostly hostile towards Russia).