We turn blind eyes to crisis all the time, we turned a blind eye to the Balkans in the 90s until very late in the day, there's no reason why this should be any different. Ukraine only became a country as part of the Soviet Union in the 1920s, prior to that it had existed as a region in various empires, there's no reason why we should suffer for Ukrainian self determination any more than we should suffer for the Kurds in their quest for nationhood, or the Palestinians or any number of other groups we don't give a fuck about.
NATO and the nuclear deterrent will keep Putin away from anything we actually care about, Russia is not an existential threat to us. The West accepts the concept of spheres of influence when it comes to us, we're just being hypocritical to not accept it when it comes to Russia and China.