after he said publicly that Ukraine could give up territory to Russia in exchange for Nato membership and an end to the war.
Key part " in exchange for Nato membership and an end to the war.". NATO didn’t let Ukraine join the last time they asked because NATO is well aware that it could lead to multiple countries having nuclear weapons (U.S., UK and France) going against Russia.
Why do you think NATO would want to give remaining parts of Ukraine the NATO membership if such a peace agreement where the NATO Ukraine remains in war with Russia? This will result in a very sensitive situation where a NATO member (Ukraine) and Russia are in a frozen war with each other. If Ukraine were to try to take their territory back, it’ll be a war between entire NATO and Russia.
I believe NATO is well aware of the fact that such a ‘deal’ is not possible.
Ukraine has consistently called for a restoration of its internationally recognised pre-2014 borders
What Ukrainian Government ‘wants’ is very unrealistic considering how strong the Russian presence is in Crimea.