In 2014 Scots voted to stay in the UK and we stayed in the UK. That's democracy.
And if Scots vote for parties that want another referendum, that's also democracy.
In 2014 Scots were told to vote No in order to stay in the EU.
In fact it turned out that Scotland was dragged out of the EU despite a majority of Scots voting for the EU.
The SNP argued that this changed the situation and there should be another referendum. They won three elections making that argument. So now there is a majority in the Scottish parliament for another referendum, and a majority of Scottish MPs support a referendum.
In this democracy, if voting for parties that propose a referendum is not enough to secure a referendum, is there any democratic way to get a referendum in this system?