It's not really certain. Of course there are foreign interests. Ukraine would prove as quite a boost to European economy (although it might be fatal for the Ukrainian economy), and one more factor in political games with Russia.
But it also should be noted that the modern Ukraine actually was created after the collapse of USSR, and its modern borders include at least two quite different territories: Eastern Ukraine and Western Ukraine. The Eastern one is much more Russian than the Western one, whose people are the most of those who now stand in Kiev and demand to continue the integration with EU.