A new national vote that respects the original Brexit referendum

Given the national vote in favour of Brexit, the UK government has negotiated with the European Union to arrive at the following plan: (fill in details).

What relationship does it have to democracy to claim that the outcome of a referendum, such as Brexit, must be carried through come what may?

What relationship does it have to democracy to claim that the outcome of a referendum, such as Brexit, must be carried through come what may?
Consider this: in a representative democracy, elections decide who represents the people. These representatives contest elections, citing positions of policy on various issues, but by no means on every one that might arise in the course of government. Moreover, once the election is over, the Parliament or Congress decides the what and how of policies to enact, drawing on advice from people who have examined the details and evolving circumstances.