Sadly, the brutal general who recently took over the reins of the Russian army is no fool. He's defending everything as hard and as skillfully as he can and he attacks without any concern about loss of life on either side. It's attrition in both directions. And the Russians are good at suffering. Which is one reason why it has taken so long to free Kreminna.
The good news is that Putin will interfere again, and when he does, the idiotic strategic decisions will recur. Doubling down is his only idea and so predictable. He was endlessly getting his troops encircled.