This is what happened in WW2. Nobody was willing to negotiate with Hitler because it was apparent that he was utterly untrustworthy, as evidenced by his repeated aggressions through the 30s before WW2 finally broke out.
It's the same situation here. Nobody can possibly trust Putin. He's utterly untrustworthy and any treaty would presumably just be breathing space and time for Russia to continue building up its forces for another invasion, just like Hitler with, for example, the Munich Agreement. The fact is that Russia has invaded Ukraine in an act of imperial conquest under the leadership of Putin, and as a result it's very difficult to negotiate with him.
It's the same situation here. Nobody can possibly trust Putin. He's utterly untrustworthy and any treaty would presumably just be breathing space and time for Russia to continue building up its forces for another invasion, just like Hitler with, for example, the Munich Agreement. The fact is that Russia has invaded Ukraine in an act of imperial conquest under the leadership of Putin, and as a result it's very difficult to negotiate with him.