Russia underestimated Ukraine as they were naive not to expect NATO to provide so much assistance to a non-member country, to a degree making it a proxy war of sorts. But then their objective was not to roll into Ukraine and "slaughter" all of the Ukrainians. But now, it seems like this will take place, as WMD will be used unless Ukraine removes its military from the annexed territories.
I don't celebrate this next likely move, I am always for peace, but if nobody is willing to negotiate and be respectful, then there will not be peace.