Cicadas clock in seventeen years apart, Apted’s once-seven-year-olds every seven, Truffaut-Léaud’s Antoine Doinel intermittently, Lelouch’s homme and femme after two decades, and Jesse and Celine at nine-year intervals. Sharing Before Midnight writing again with stars Ethan Hawke and Julie Delpy, director Richard Linklater’s Gen X couple returns, unmarried married folks with children.

They first met in their early twenties, in Before Sunrise’s one-nighter starting on a train nearing Vienna, then again for Before Sunset when she came to his book-tour reading in her Paris, both times on the fly with schedules and other places to go on to. After time in New York, with twin daughters Ella and Nina (Jennifer and Charlotte Prior) they now live in the City of Light, more settled, less rushed, but like most around-forty-year-olds still dependent on some forces outside their couplehood.

In her case, it is the more fulfilling environmentalist job opportunities she feels she has passed up in order to balance work with mother- and wife-hood and housekeeping. Deep down are related, repressed resentments of his easy acceptance, or simple self-centered ignorance, of her personal woman’s sacrifices, mixed with dissatisfaction with machismo, sexism and in-bed assumptions.

Granted, these are vindictive spitouts she hurls in anger during a climactic half-hour argument, and though they are dredged up and aimed to hurt, still they are there with some basis in what is her version of their reality.

The slice-of-life film is not female tract, but the male partner is oblivious of her inner feelings. An acclaimed writer (as is Hawke) who sees more deeply into his created characters modeled on others in his life than into this woman by his side, he is at present worried about early teenage son Hank (Seamus Davey-Fitzpatrick), who as the film opens is boarding a plane to fly back to his divorced mother after vacationing with dad and his present three-female family.

Guiltily concerned that the boy throws like a girl and should have a man around the house, Jesse toys with their moving to Chicago, where Celine foresees that she will have scant work possibilities and they will be Hank’s babysitters for the disliked ex-wife.

This airport adieu is in southernmost Greece. Novelist Jesse and family have been invited guests at the seaside villa of older fellow writer Patrick (Oscar-winning cinematographer Walter Lassally, at eighty-five in his first acting rôle), three generations of whose own family and friends are there this day. Sprinkled into the women’s dicing and slicing for salad there is woman-talk, and there is man-talk outside, and there is witty, convincing spontaneous-sounding table-talk -- “but every word is scripted”-- much of it about couple relationships and how different participants deal with partnership perks and pitfalls.

Driving back earlier from the airport and skipping an educational stop at ruins since the twins were dozing, Celine and Jesse had talked, too, for a quarter-of-an-hour joked, probed, disagreed a little, reconciled, each revealing some unsuspected personal tidbit or two to the other. Such realistic and perfectly reasonable companionship will continue as, by themselves, they later walk around and visit a small Byzantine chapel. And it will continue more at the port’s best hotel, chosen and insisted upon by their hosts as a going-away returning-home present sans children.

The temptation to revisit this talky couple at the half-century mark will probably look too strong to resist. But the actors sense that “invariably we will . . . let people down,” and the hope here is that this is the last of them. Their path of self- and mutual-discovery strikes true and lovely this third go-round and in its predecessors. So leave well enough alone. The heart of life lies in its day-to-day existence and ordinariness as viewed by others, and the screen can take only so much mundane outer uneventfulness, whatever the emotion beneath.

(Released by Sony Pictures Classics and rated “R” by MPAA.)