Valentine’s Day can be a fraught occasion for couples, but if you’re single, the pressure is even worse. Back in 1995, single women looking for help in navigating the dating landscape could turn to the book “The Rules: Time-Tested Secrets for Capturing the Heart of Mr. Right,” which issued straightforward instructions like “Let Him Take the Lead” and “Don’t Rush Into Sex.” “The Rules” was mocked by some women for its seemingly antiquated, anti-feminist messages, but it clearly spoke to the many readers who turned it into a surprise bestseller.

Today,...