The US support of South Korea is the only reason the North has not invaded and taken control of South Korea. Siminarly, there was no deal that could have been made with Russia that would have preserved Ukraine in 2014, as we have seen, and there is no deal to be made with Russia that would preserve Ukraine now. If Ukraine cannot stop the Russians on the battlefield, then Russia will eventually take all of Ukraine, and Ukraine cannot stop Russia without support, weapons and ammo, from the West.
Let's not be distracted by Putin's bullshit about what caused this war. Putin invaded because the Ukrainian government refused to be ruled by the Kremlin. Any deal with Russia that leaves Ukraine vulnerable to Russian attack will lead to all of Ukraine being taken over by Russia, and any Ukrainian who talks about Ukrainian sovereignty or independence will be branded a Nazi and thrown in prison or worse. Clearly, there is no deal to be made with Russia that will preserve Ukraine as a sovereign state.