NATO turned what was originally intended to be a mostly peaceful show of force like the temporary invasion of Georgia into a war of attrition.
Remember WWI when the lines were pretty much static for years and then suddenly it was all over?
That's what's happening here. Russia has most of Donbas plus a buffer zone in some other regions that directly border Russia. Ukraine is throwing men at the front lines for Russia to kill but is running out. Territory held is largely irrelevant compared to the number of men killed and weapons destroyed.
Hence the desperate calls for 'ceasefire' on the Western side because they know Ukraine can't last much longer.