Sex was rarely far from the surface, but in the ’50s and ’60s it really started to announce itself: The stars seemed either made of all the sex in the world (the Marilyn Monroes and Jane Russells) or none of it (Doris Day, the great movie virgin, defending herself against Rock Hudson’s length and hair and teeth). And if right now looks bad for the romantic comedy, the frenetic 1970s were almost worse. Some of the movies may have been better — “What’s Up, Doc?,” “Shampoo,” “Annie Hall,” “Starting Over” — but their approach to relationships was cockeyed. The people in them seem to have soured on love stories, and on one another. It was only as movies swelled into blockbusters that the conventional romantic comedy flourished again, repotted inside “Star Wars” and “Superman” and, a few years later, shoved into the Indiana Jones movies and “Ghostbusters.” And the old battle-of-the-sexes plot came back in two adventure fantasies Michael Douglas and Kathleen Turner made together in the first half of the ’80s.

This was the other period I grew up on, a modern gloss on the classic style: Holly Hunter over- and outthinking William Hurt, Susan Sarandon tying Kevin Costner’s tongue, Goldie Hawn squaring off against Burt Reynolds or Kurt Russell. Romance was giving in to 1980s corporate fever, and expanded to obsess over work and the workplace — in “Tootsie” and “Baby Boom,” “The Secret of My Success” and “Working Girl.” The stakes were bigger than companionship; the romance was, in part, with the office, and what it meant to be a woman working in one. In 1988, two of the five Best Picture nominees at the Oscars were romantic comedies: “Broadcast News” and “Moonstruck.” So, arguably, were two of 1989’s: “Working Girl” and “The Accidental Tourist.”

Then, at the end of the decade, a movie came along that restored the genre to its easiest, smartest, most essential self, deploying the drawbridge structure as an act of discreet feminism and presenting two gainfully employed potential partners whose workplaces we never see. “When Harry Met Sally” opened in the summer of 1989, and it was a moon-landing sort of event, not because of the money it made but because, as written by Nora Ephron and directed by Rob Reiner, it formalized the genre with a thesis. On the last day of college, in 1977, Sally Albright (Meg Ryan) agrees to drive a friend’s boyfriend, Harry Burns (Billy Crystal), from Chicago to New York. The drive alone — 15 very funny minutes — would have made the movie. He’s crude, and a lech, and he hits on her, which she can’t believe (“Amanda is my friend! ”). They argue about the end of “Casablanca.” She insists they just be pals. He says, to her bafflement, that friendship’s impossible: No man could coexist platonically with a woman, because he’d rather be having sex with her. Upon arrival in New York, she offers her hand to shake: “It was interesting.” After that, the credits honestly could have rolled — but the movie skips ahead five years for a second encounter, then five more for a third. We watch two adversaries mature, warm to each other, then age into each other. Each is given a respective life and point of view; the molecular composition of the movie is different when they’re together than when they’re apart. They don’t have to fall in love, but somebody has to win their argument, and it turns out to be both of them — she wouldn’t have the sex without the friendship. So, drawbridge, and a draw.