Sorry, but that is not true. Ukraine and EU never had signed an agreement. Yanokovich tried to renegotiate the terms of the agreement to be signed, but the EU refused, and so he declined the deal.
What is also lost in the propaganda is that there were definite real conflicting interests between different parts of Ukraine. To put it simply; the western agrarian part of Ukraine, and Kiev with its central administration would have gained from a deal with EU. The eastern industrialized part of Ukraine would have lost economically, at least in the short and medium long run. And that would have been the case even without a Russian customs barrier. (There are several papers, also from EU funded researchers showing this.)
Thanks, I oversimplified.