The war is a stalemate rathole for everyone. Russia thought they would prevail easily like they thought in Finland in 1939. In both cases they were wrong, and 1939 can be a lesson.
Eastern Ukraine is ethnically and linguistically Russian. They voted for the Russian aligned party in all the elections.
Driving Russia out is unrealistic. Ukraine can't do it, and involving other countries risks escalation.
The lesson from 1939 is that after some early success, the Finns were forced to negotiate and ceded land to Russia, which had learned it had bitten more than it wanted to chew.
Try critical thinking