If this does go tits up for the Russians fairly sharpish, I wonder how Putin will react, and how he will sell it to the folks back home. My guess is that there will be an attempt to call 'foul play' by the British and Americans, some far fetched idea about all the Ukranian troops being given secret drugs or something....
I think the only thing they can do is what they have been hinted at recently in some russian media, is that they make out they have been fighting all of NATO and not just Ukraine, so they can pretend that strong russia managed to hold on against the world but had to back out eventually to save their troops but only after completing their demilitarisation of Ukraine or something along those lines.
Im not sure how many will buy that but considering "european" russians have barely featured in the war it could be enough to keep the main population under control.