When empires or political unions breakup there is always violence.They appear to have a Boris like problem - who to replace him with. The britannica has a decent run down on the break up
That is because the imperial powers redraw original borders of the subject states in order to further the wider imperial interests.
There is nothing unusual about the conflict in Ukraine, it is a former member of a forced political union, different ethnicities and religions were made to live within borders created for the overall security of the Soviet union.
When the glue of oppression that held the Soviet union together dissolved, then the original ethnic and religious identities started to reassert themselves in the form of ethnic nationalism.
That is when the violence comes in, modern Ukraine is a state created by a former authoritarian power, that authoritarian power has now gone, so, it is only natural that the different peoples who lived within the borders of what was essentially an artificial state, now want to exercise their own right to self determination.
One solution would be to hold internationally supervised referendums in the disputed terroritories to find out what these people actually want.