When in the history of ever did a nation willingly withdraw from its enemy before even holding peace talks?

Did the US withdraw from Mexico before they started hashing out Guadalupe Hidalgo?

Did Germany withdraw from Russia before negotiating Brest-Litovsk?

Even the 'we do not negotiate with terrorists' US negotiated with the Taliban before leaving Afghanistan.

It’s a deal, and withdrawal is one of the terms. You don’t do it before the deal has been made. That gives up all leverage.

And Ukraine has already demanded they get absolutely everything, including Crimea. If you want a deal to be everything you want and nothing you don’t, you need an unconditional surrender, not peace talks. Good luck getting Ukrainian tanks into Moscow.