Russia has no excuse and neither does NATO. The best case scenario is both countries lay down their arms and have socialists take power. Unfortunately we don't live in that kind of situation, so the only thing I can advocate is both NATO and Russia cease fighting. Ukraine shouldn't ally with NATO because NATO shouldn't exist.
What negative effects would Russia be feeling? I don't know, personally I thought Russia entering the war was a bad call and a strategic mistake. I can see the reason why it happened while still saying it's an open act of aggression. Russia probably could have negotiated with Ukraine about Donbas/Luhansk through better oil deals or something, no idea. Possibly could have tried straight up purchasing the land that Russian separatists occupied?
But Russia probably had reason to distrust diplomacy with Ukraine ever since 2014. For context, I believe that 2014 happened specifically because Ukraine's previous government was becoming too close to Russia and it made NATO nervous. I could easily ask, what negative effects would Ukraine be feeling if they hadn't had a western backed coup? Ukrainian president Viktor Yanukovych floated membership in the Eurasian Economic Union, which set off protests that were capitalized upon by western nations. Would it had been so negative had Ukraine entered a formal economic alliance with some former Soviet states? Who knows now.
The new president, Porochenko, was much harsher on Russian separatists in the east than his predecessors, which started the Donbas war in earnest. That's the moment above any I can point to that started all of this. Maybe if Yanumovych had remained president there could have been a more peaceful solution to Donbas. Who knows now
Yeah but this is all speculation and we live in reality. The reality is the war should cease immediately, for the benefit of people in Ukraine, Russia, and all refugees from the region. Only way I see that realistically happening is if NATO disengages and Ukraine loses territory.
Maybe once fighting finishes something new and better can get negotiated, but I'm not holding my breath that neoliberal countries like this know how to resolve long standing conflicts.