If you put on your realist hat, there are two options. One is for NATO (or another European military alliance) to be so powerful and cohesive in their relation

If you put on your realist hat, there are two options. One is for NATO (or another European military alliance) to be so powerful and cohesive in their relations to Russia, that Russia have no choice but to deal with it. This was presumably the false assumption that lead to the current war. (I really, really hope it was a false assumption). The other option would have been to thaw relations, perhaps acquiescing to a few demands and showing more compromise. Say what you want about Russia - and there's a lot bad to say. But much worse actors have received much nicer treatment by the west. Think about everything that's been done to accommodate China since the end of the cold war, to say nothing of the likes of Saudi Arabia. Instead a middle path was picked, and now we have war.