I am about halfway through Richard Sakwa's book, FRONTLINE UKRAINE, Crisis in the Borderlands. This is an excellent book, and the first one I've found printed in English that seems to give an evenhanded account of the problem. I will not attempt to post a review of this book---I just recommend that you read it yourself. The problem he describes is complex enough that the 255 pages he writes is in itself a brief summary. Parts are densely written but no more so than necessary to describe the complex historical, economic, and geopolitical forces in play here. I can't summarize it, but I'll give you a metaphor. [This is my metaphor---not the author's]
Imagine a large hockey arena, with two goals; one at the east, and one at the west. There are seven or eight teams on the ice, representing two different leagues. None of the teams have decided for sure which league they want to belong to---some would like to belong to both, but that isn't allowed. There is internal dissention within the teams over this issue, with violent quarrels breaking out, and some members switching allegiance to other teams. All the players on the ice have known each other for a very long time, and carry old grudges that go back as far as anyone can remember. Meanwhile, a dozen pucks are in play, bloody fights on the ice break out from time to time, and there are no referees. Everyone accuses everyone else of bad faith----usually for good reason. Occasionally, someone makes a good faith effort to stop the madness, but the old wounds and old grudges are too old and too deep.
The drunken fans are not sure who they are cheering for--or why. They quarrel among themselves noisily, and eventually, some of them will probably set fire to the arena.