The problem with NJ's otherwise excellent analysis is that the EU has, in fact, always understood that the Commons would struggle to support its deal, even before the Commons did. But, then again, what business is it of theirs? The EU set out its negotiating position early -- which essentially amounted to something along the lines of "if you want to leave then leave, and if you don't want to leave then you kind of have to stay" -- and has stuck pretty doggedly to it ever since. The logical consequences of that decision, coupled with Theresa May's and the ERG/DUP's "red lines", have essentially meant that the UK must choose between a rotten deal (but, it has to be said, one that does lead, ultimately, to Brexit!) that destroys sovereignty for a decade or so, and a "no-deal" that wrecks the UK's economy -- and never mind that even with a no-deal exit the UK still would have a lot of work to do to decide its future relationship with both the EU and the world.
No doubt other versions of the deal could have existed. But they weren't explored or taken seriously from our end. Not without reasons, but the point is still that the Withdrawal Agreement reached has been shaped by the UK's demands, rather than the EU's. In the case of the Backstop, this is literally true: it was a UK-based initiative, proposed when it was suddenly understood that the Irish Border presented a problem and a contradiction* between separate Customs arrangements (a UK red line) and the integrity of the Good Friday Agreement.
But anyway. The EU made its best offer given the UK's negotiating position, and is only surprised in as much as they can't quite understand why some MPs don't see that it's the UK's own negotiating position that has led to this, rather than EU intransigence. No wool has been pulled over anybody's eyes, in that sense. When Cox published his legal view of the effect of Monday evening's developments, I don't think anyone in the EU was surprised or even disappointed to see that he still felt the UK could be stuck indefinitely in the Backstop. That is, after all, the point: it is there to act as a last resort to stop the Irish Border from ever reverting to a closed one, if nothing else can be found. It stands to reason that the Backstop would have no use whatever if it were forced to end by a given date.
Meanwhile, it seems that the Brexiteers may soon discover that their dreams of No Deal aren't dead because the EU decides that it's not worth wasting any more time waiting for the UK to decide what it wants. Now there would be an irony: the EU taking away the UK's sovereignty for one last time to deliver exactly what Hard Brexiteers have clamoured for...
*Yes, we've argued this point already, and some will disagree. Can't be bothered going over *why* this is true any more. What matters for this post is that the EU didn't ask for the Backstop; we did.