Yes, and that’s not in the best interest of Ukraine. So Ukraine doesn’t want to lose all of that territory, but Russia wants to gain it, and Ukraine thinks it is capable of defending it’s territory, while Russia thinks that it’s capable of defeating them.

That’s how you get a war. To get peace negotiations you need one of, or both of the nations to decide that they’ve had enough casualties or other loses, and that they’re ready to settle down for less. Neither of them have decided that.