This is right in the EU's backyard. If it were to heat up they'd actually have to deal with things like refugees and the possibility of war spreading to their members. They probably also want to be very explicit about their (lack of) obligations in this case, I mean people are already acting as if this calls into question how steadfast they'll be in defense of eastern EU members.
Another option is that both the EU and Putin know Russia does not have the conventional strength to attack the EU, but does have the manpower to attack other unaligned countries. And so, the EU has decided to prioritize their other interests over standing up to Russia.
But don't take it too seriosly, that was long ago, now our brand new and most competent foreign affairs sock-puppet goes with the flow.