That period shook loose her memories of Benny, the older, married party activist whom she lived with in her 20s, which she first recounted in a 2013 biography.

“It has, of course, followed me and shaped me,” she said. “With the #MeToo campaign, almost every woman recognizes that something has happened to her that we thought then was kind of natural, that we look at differently today. Why did we stand it? Why did we accept to be talked to like that?”

For a moment she let her mind dwell on that last meeting, when Benny, who had been drinking, held a knife to her throat. “He felt so desperate,” she said. “I did not want to talk to him anymore, I wanted him to leave. It was really the last sort of expression of: ‘I decide. I am the one.’ It was a demonstration of power.”

After escaping that room, she was different, less naïve. Within a few months, just 25, Ms. Wallstrom had won a seat in Parliament. Five years later she married a carpenter named Hakan, as calm and quiet as Benny was combustible. She raised two sons and buried a third in infancy, an experience so painful that it made her, she said, “kind of fearless.” Even when her job required her to spend days listening to women’s stories of abuse, she rarely spoke to anyone of Benny.

“It’s more subconscious, in the way I can understand these women,” she said. “I understand the feeling of helplessness. It’s such a degrading experience, anything like this, where you are under the power and control of somebody else.”

Image Ms. Wallstrom at a Barents Euro-Arctic Council meeting in Arkhangelsk, Russia, last month. Credit... Alexander Shcherbak/TASS, via Getty Images

Ms. Wallstrom raised eyebrows, in 2014, by announcing that Swedish foreign policy would from that point forward be focused on feminist principles, and waves of international press coverage followed.