On Sunday afternoon, I was at "the Do Over", an annual event in Brooklyn, N.Y., which was attended by thousands of people, mostly young black professionals looking for a good time.

In the crowd, I spotted a woman who left no doubt about why she’d shown up that day—not for the music or to hang with her girls or stunt for the Gram. She was looking for a man. How did I know?

She was wearing a sign on her back that read, “I just came here to find a husband.”