Lee Celano for The New York TimesDylan Langlois, center, and Kasandra Larsen said goodbye to a friend as they prepared to move out of New NEW ORLEANS, Feb. 15 — After nearly a decade in the city of their dreams, Kasandra Larsen and her fiancé, Dylan Langlois, climbed into a rented moving truck on Marais Street last Sunday, pointed it toward New Hampshire, and said goodbye. Not because of some great betrayal — they had, after all, come back after losing everything in Hurricane Katrina — but a series of escalating indignities: the attempted carjacking of a pregnant friend;...