You think you know modern romance? Think again. A seismic shift is underway in China, redefining how young couples connect.

For Cindy Zhong, like many young Chinese women, a relaxing night used to mean curling up with a steamy story about two men in love. Then her favorite authors, and their tales, started disappearing.

Based on Meng Zhong De Yi’s novel, which is literally translated to “Pragmatist’s Love,” “Love Story in the 1970s” is a ...