What did she lie about? She had three red lines. Designed a system that would adhere to those red lines and people hated it and so kicked her out (even though Boris voted for her deal at the third time of asking). Boris made the same three promises. Completely rolled over on the border down the Irish Sea and yet somehow people loved him for it. One stuck to their word and got punished for it. The other lied his way through the leadership campaign and didn't deliver what he promised.
Her EU Withdrawal Bill offered Parliament a vote on a second referendum to woo a Remain Labour Party under Corbyn. She was dead meat among Tories from then on. Boris came in, said **** Labour Remainers, I'll get Brexit over the line and the UK electorate awarded him with a massive majority.