Her solution: Men have to wait for a woman to reach out — they can’t initiate the conversation — so rather than feeling rejected if a woman doesn’t reply to their pickup line, they feel flattered if she reaches out to pick them up.

Emily Witt, the author of “Future Sex,” which documents her experience as a single person in her 30s trying to understand dating and courtship today, thinks the app helps clear up confusion. “A lot of contemporary dating, a lot of the kind of sense of unease,” Ms. Witt said, “comes from people not knowing how they’re supposed to ask and roles they’re supposed to play, because so many of the dating rituals are so patriarchal. Yet even so, a lot of women are still reluctant to ask a guy out. So I think the revolution of Bumble is taking that uncertainty completely out.”

Ms. Wolfe did not initially plan to change the dating game. She was 23, unemployed and living with her mother when she took a trip to Los Angeles to visit a fellow alumna of Southern Methodist University. The hot water went out, so they went to another friend’s house to use the shower. That friend was Mr. Mateen. That night, they had dinner with his buddy Sean Rad, who was working at a tech incubator owned by IAC, which would eventually become the birthplace of Tinder. He needed someone to run marketing, and Ms. Wolfe was available.

She didn’t have a career plan, exactly, but she had had plenty of jobs. In college, she sold tote bags to raise money for animals affected by the BP oil spill. Later, she volunteered in orphanages in Southeast Asia, excitedly phoning home to tell her parents she was going to start a travel website. “They were like, ‘Can you just focus on not getting malaria?’” she said. After college, she spent a month in a photography program in New York and worked a few odd assistant jobs before moving back in with her mother.

At Tinder, Ms. Wolfe said, she took the app to S.M.U., got sorority women to sign up, then immediately crossed the street to the fraternities and told them all the hot girls were on the app. When she started Bumble, she did much of the same, taking it to universities, signing up college women and assuming — as good marketers do — that where the women went, the men would follow. It was a crowded market, but Bumble now claims 800 million matches and 10 billion swipes per month. It ranks second in top grossing Apple downloads in the Lifestyle category, second only to Tinder.