Street disturbances and anti-government demonstrations have been on-going in Ukraine for some months now. We've come to understand these as being an east vs. west sort of conflict, essentially Russia vs. the EU.
Professor Nicholai Petro has written an extensive analysis of the issue for The National Interest. He says the Russian-speaking peoples of the east and south and the Ukrainian-speaking peoples of the north and west are, effectively, two cultures, united in mutual distrust. Petro's analysis is good, his proposed solution appears impossible to implement.
The CIA World Factbook indicates the Ukrainian group is larger, somewhere between 67% and 78% of the population. Their numerical advantage is offset by Ukraine's proximity to Russia.
Unfortunately, Russia is not noted for restraint in its interference in the internal affairs of its neighbors. Ask the Georgians about Russian bullying.