Look it up again.
Pro-Russian president won like 55-60% there-
No. "Pro-Russian" president Yanukovich ran his election promising to support the EU agreement. Then he changed his mind.
I would add that Yanukovich has now said that it was a mistake to call Russia into Crimea.
I've already documented several polls on other threads that show about 30% of folks in Luhansk and Donetsk want to be annexed by Russia. I've also documented that even a smaller number in those two oblasts voted against independence from Russia back in the early nineties. And I've also documented that ethnic Ukrainians are a fairly large majority in those two oblasts.