This Op-Ed has been updated to reflect news developments.

LONDON — My first attempt to charm Theresa May was eight years ago, in the grand surroundings of the State Dining Room in Downing Street, where a couple of hundred women had been invited to a reception for International Women’s Day. Mrs. May, then the home secretary, arrived to the event late and perched by a table looking uncomfortable and alone. She was the only minister not surrounded by a jostling crowd. I told a gaggle of female correspondents that I was going to talk to her. “Don’t bother,” they said. “She’s a blank wall. She never tells you anything.”

I didn’t believe them. In general, politicians need journalists to exchange gossip, spin, insights and facts. I took my glass and introduced myself. Mrs. May gave a small tight smile. Every question I asked, from how she was doing to what challenges she faced at the home office, was batted away with monosyllables. I was baffled. She clearly saw no point in creating a relationship, or explaining any of her thinking to me.

This would have been an irrelevant encounter with an unimportant hack except that practically everybody, from fellow ministers to advisers to European leaders, turns out to have experienced a version of it. Mrs. May’s extraordinary inability to develop or grasp the critical importance of alliances, friendships, coalitions and mutual understanding in politics has destroyed her premiership — and derailed the Brexit process from its beginning to its calamitous stalemate today.

This week, Mrs. May sealed her fate. She announced to her Conservative Party that if they voted for the Brexit deal she negotiated with the European Union — and which Parliament had, humiliatingly, voted down twice already — she would finally resign. On Friday afternoon, Parliament voted down the deal for a remarkable third time. What happens next with Brexit remains terrifyingly uncertain and it’s not clear how much longer Mrs. May can hang on. But one way or another, her days are numbered. And the damage is done.