Complete lack of foresight from the start when they decided to back Brexit. How did they suppose things would pan out? Didn't take a genius to see that the hard brexit they craved would have meant customs and border checks as they share a land border with the EU.
I think the penny has finally dropped, all the different brexit scenarios we have heard about such as Theresa's deal, Boris's deal, no deal, Norway model, Canada model. None of these suit the unionist position better than what we already have, Remaining in the EU. Unfortunately for them that ship sailed long ago.