But I didn’t know.

My instincts had been telling me for a couple of weeks, as we wound down towards the summer holidays, that something was up. Something was wrong. Sean had always been the one to look on the bright side, to make the kids laugh, to bring me a gin and tonic when I needed cheering up. In the unconscious allocation of roles in our marriage, I was the organiser, the rule-setter, the guardian of boundaries. Sean was the light to my shade – always open, funny, patient, the optimist of the family.

Now he was defensive, secretive, serious. Distracted, constantly staring at his mobile. Perhaps work was getting on top of him – hassle from his new boss? He’d half-suggested that maybe he should stay at home this week, because of work. Or perhaps it was his fear of reaching forty, which seemed to grow stronger as his birthday drew nearer. Some kind of midlife crisis? I’d asked him if he thought he might be depressed – if I knew what was wrong, we could tackle it together. But he had brushed my questions aside, insisting he was fine.

I flinched as he touched my thigh.

‘Kate?’

‘Sorry,’ I said, forcing a smile. ‘Miles away.’

‘How long until we turn off this road?’

I checked my phone.

‘About another ten minutes.’

He took his hand off my thigh and moved it back to the steering wheel. The warmth of his fingertips lingered for a moment and I tried to remember the last time I’d felt his touch, the last time he had reached out to me. Weeks? A month?

The fact that you’re even thinking it means something isn’t right. That’s what Rowan would have said. The holiday had been her idea, two years in the planning. Rowan, Jennifer, Izzy and me – best friends marking our fortieth birthdays with a week together in the south of France, husbands and children included.

‘Grand,’ Sean said. ‘You OK?’

‘Fine. Just want to get there, get unpacked.’

‘Have you heard from Jennifer and Alistair?’ He glanced up at the rear-view mirror. ‘Since they lost us?’

‘No, but I’m sure they’re not far behind.’

‘I told them I’d lead the way and they could follow.’

I turned to look at my husband. It wasn’t like him to worry about Jennifer and her husband – he got along with them OK but had little in common with them, apart from me.

‘You know what Alistair’s like,’ I said. ‘He could get lost in his own back garden.’

‘Sure, I suppose you’re right.’

I went back to staring out of the window at the lush green vineyards rolling past, dark grapes ripening in the summer heat. Off in the distance, the conical black towers of an ancient chateau stood out against the skyline.