She’s hardly the archetype of destitute single moms. But a once-pampered girlfriend who thought nothing of jetting to Paris to grab a $10,000 dress may be about to do poor women in Quebec a huge favour. The 34-year-old is suing her billionaire ex for $50 million—plus $56,000 in monthly payments—on grounds that she and her three children got used to a lifestyle during the former couple’s 10-year relationship that her current support payments of $35,000 just can’t maintain. The two were never married, and in Quebec common-law partners don’t enjoy the sort of legal protections in place in other provinces. The case could affect more than a million common-law couples in Quebec.