Problem is, as always "Trust"
There are no trust left between Russia and Ukraine, each side will see the other side of lying, on the other hand, you have Russian doing not really a good job to warrant a cease fire to begin with (it's not like Russia is in anyway threaten Kyiv) so without one side at underhand, and both sides don't trust each other, there can never be negotiation.
The only thing can push Ukraine into Negotiation (as I said, Russia is not really at a position advantage enough to call for one) is NATO, Ukraine will most likely talk if NATO guarantee their security future, but then would Russia comply? Seeing not wanting Ukraine join NATO is one of the reasons why Russia invaded.
So, the end result sadly is, Ukraine won't trust Russia for not ever going to attempt this again, and Russia will not trust Ukraine not to join NATO, hence the war continue.
The only reasonable point this war is going to have a cease fire is one side dominating the other. And at this stage, neither Russia nor Ukraine have the upper hand.