Theresa May, knowing...
A) her deal won’t get through Parliament
B) defeat would mean she has to quit
... instead takes her deal (ie Leave option) vs no Brexit (Remain) direct to the country in a People’s Vote.
She can plausibly claim that implementing the result will be easy, because EU has agreed her deal already, and remain is a snap of the fingers and done.
After all, if she can invent an entirely fictional “Brexit dividend”, why not do the same for Remain?