It's not unusual for politicians to flip flop on positions, however May has said from day one that she will NEVER allow a second referendum. That's the position where she has put all her political capital and credibility. But it looks like she will have no option but to flip flop.

So the two options are: Hold a vote on her terrible Brexit deal, the deal absolutely gets voted down, she then loses a vote of confidence in Parliament and we face a fresh election (where her conservative party will have no chance of winning). Or cancel the vote, opt for a second referendum which wouldn't be accepted by the British people and the chances of violent protests increase greatly.