It isn't Ukraine's fault at all but I don't think that we can reduce this to Ukraine is a singular state of people who have been invaded by an aggressor out of the blue, there's quite clearly far more to it. Anybody who suggests we should fight Russia is just war-mongering to advocate another kind of empire building within Europe.
Ukraine isn't a huge part of the European sphere, it was only recently a socialist vassel state of the ex-USSR. Would you say that Ukraine has more history and more in common with the UK or Europe than Russia? That's rubbish. Russian is even an official and majority spoken language in Ukraine.
Even a reformer like Gorbachev supported the annexation and subsequent referendum within Crimea because the people of that area have far more history and commonality than Europe. I don't support the annexation but then I am not Crimean and as we can't trust the referendum there's no way of knowing what the Crimean people really wanted.
The irony is we in the west and Europe are not exactly a moral authority on geopolitical meddling, invasions, military interventions and that kind of thing. We should be acting as a mediator because ultimately this is a regional conflict/dispute, it shouldn't be something that Europe dies on the ditch for.