This is one of the core problems. Zelenskyy cannot back down. He has too much political capital invested.
If we withdraw support and more or less compel a cease-fire as a consequence, he falls. He knows this, and he has been playing to Western media to bring popular pressure to bear, because his political survival depends upon continued Western support.
Putin also knows this, which is why he has been trying to end that support by steadily ratcheting up the risk level associated with continued support.