If you think that Ukraine will retake Russian-leaning areas in the East through partisan fighters, I disagree fully.

I watch (with sub-titles) a Ukrainian army officer who makes infrequent YouTube videos. This guy is 40+. Even he has said that Ukraine understands that trying to reintegrate these areas, that want to be part of Russia, back into Ukraine would be difficult, and questions whether it would be worth the effort. I agree with that Ukrainian.