Given the fact that we start from a position of regulatory equivalence and that it is in the EU's economic interests to agree a deal with the UK, it should have been straight forward. But it takes two to tango, we can't force the other side to act reasonably. The EU was motivated by a desire to punish the UK and deter other potential leavers. If the referendum can be invalidated simply by the other side refusing to play ball, why would they ever have any incentive to do so?
Let's not forget that agreeing an acceptable deal has been severely hampered by Remain politicians in this country who have acted to undermine the UK's negotiating position e.g. removing the threat of no deal. Some like Tony Blair have even gone to meet with Brussels officials to encourage them to adopt a hardline.
Remain MP's justify their refusal to honour the referendum result and in many cases general election promises by saying it is only no-deal that they are opposed to. Well in that case why did they vote against May's deal? And in the unlikely event that Boris agrees a deal with the EU, why will most vote against that too?
As others have said the referendum was not dependent on whether we achieved a deal or not. The prevailing issue was one of sovereignty. "Take back control" was the Vote Leave motto. Remainers claim that leavers didn't vote for no-deal so why do they refuse to put that to the test? The Labour party's policy is to negotiate a severely watered down Brexit in name only, which they will put to a referendum where the only other choice would be Remain. As for the Liberal Democrats, their official policy is now to not even have one at but revoke article 50 completely if they get an overall majority, something they could achieve with only 35% of the vote. That's if we ever get a general election any time soon, the opposition parties are currently blocking this for fear they will lose. Plus both Jo Swinson and Caroline Lucas have said even if Leave won again in a referendum they would vote against it in parliament
I'm afraid the acceptance of democracy argument doesn't wash when you put it like this. I don't doubt your sincerity Noel but I do Remain politicians. They simply want to stay in the EU and they're not overly fussed how they achieve it.