Russia overtly wants a sphere of influence that includes (among other neighbors) Ukraine, and Ukraine isn’t voluntary giving in to it's desire for that, so Russia keeps waging war and taking bits of Ukraine. Ultimately, that obviously ends with Russia taking the whole country to achieve that goal, unless it gives it up.
Russia would rather have surrender without further invasion (it's too late for “without war”), but it's also clearly willing to fight an escalating war to achieve it's goals.
