So we’re all agreed Ukraine is winning, Russia can’t ultimately…so what on earth is Donald doing?!
I don't know about all agreed, but that's certainly what I think.
Russia could win if we gave up supporting Ukraine (doesn't seem likely), and Russia could half win if Ukraine decided that losing their land in exchange for a lasting peace was worth it (eg, if Russia eventually came to realise they couldn't take over Ukraine, and couldn't stop the war and rearm without Ukraine joining Nato etc).
As for Trump - I honestly think he's just a bit (I'm playing it down) stupid. I think that Trump believes Ukraine can't win (for example it's true that Ukraine can't force Russia out of the occupied lands), so he figures he'll make a deal that Ukraine have to accept, we'll give him the Nobel peace prize, and that'll be that.
But I don't think that's the reality. Ukraine would be mad to accept a deal that a) gives Russia their land, and b) doesn't give them cast iron security over the rest of their country. If they were to do that, it would be suicide. It's guaranteed that Russia would build a much bigger army, and invade again.
It's possible that Ukraine could give up their land in exchange for Nato membership, but that would be a tragedy.
I pray that my armchair analysis is correct, and that Ukraine can continue this war until Russia collapses and withdraws, so that Ukraine can get it's land back, and join Nato (and the EU).