At a market in Meyzieu, a small commune on the outskirts of Lyon, Kheira Vermorel eyed a box filled with potatoes, wondering if the sizeable spuds would be enough to soothe tensions at home. For weeks – specifically since France’s president, Emmanuel Macron, plunged the country into shock snap elections – she and her husband had been at odds. “It’s been really hard,” she said. “I’m worried it might lead to a divorce.” At the heart of their weeks-long dispute was the forthcoming ballot. Last election Vermorel, who moved to France from Algeria 35 years ago, voted for Macron. This...