Grace (Annette Bening) and Edward (Bill Nighy) are a many-years married couple. She bickers and snipes at him, he slumps his shoulders and takes it. Over 30 years together, they’ve found lots of things to agree and disagree on, but they’re definitely united on one front: son Jamie (Josh O’Connor) doesn’t visit nearly enough.

When he does visit on this particular weekend, his mother does her usual thing, wasting half the visit dressing him down for not visiting her enough, thus making him less inclined to visit next time. But that’s her way. She speaks her mind. He’s used to it. He also fends off her religious overtures, and ultimately she goes off to church alone, which is when his father surprises him.

After some hemming and hawing he just says it: “I’m leaving your mother.”

Now hopefully we’re all groaning on the same page here: he’s told his son before he’s told his wife. And of course his wife feels blindsided, hurt, and not a little angry. Mostly that there was no warning. She never saw it coming. Now, Edward has some excuses for this: that she’s domineering, that she’d only try to stop him and his mind is fully made up. But to her, this is a 30 year relationship we’re talking about, and it’s worth a little effort, worth an attempt or two to save it. Not that this has stopped her from any of her heated squabbles.

Edward is not a complete idiot. He’s timed this so that he could abandon his wife quite quickly, leaving his son to pick up the pieces. Grace is understandably bitter and Jamie feels trapped. His mother isn’t just sad, she’s depressed, perhaps suicidal. It’s a lot to ask of a son.

This film is based on writer-director William Nicholson’s own experience of his parents’ divorce. It’s a little light on plot or direction, driven mainly by some great performances. Neither Grace nor Edward come off as particularly admirable people but Bening and Nighy give them a little more sympathy than is truly deserved. The collapse of a marriage is always an aching thing. The grown son being pulled between two grieving parents acts as a proxy for the audience, but because neither character comes off as entirely blameless or even likable, we actually feel pulled in neither direction. Instead, we remain unmoved somewhere in the middle, which doesn’t make for a very bracing or rewarding trip to the movies.