A widow speaks hauntingly about the coronavirus death of her husband, the folk-country musician John Prine. A small-town undertaker grieves over losing so many familiar faces to COVID-19. A cancer doctor forced to deliver bad news virtually laments the loss of human connection. Illness and death are the pandemic’s most feared consequences, but a collective sense of loss is perhaps its most extraordinary. With job layoffs, canceled family visits, shuttered restaurants and closed gyms, the pandemic has spread grief by degrees around the globe. Experts say even seemingly small losses can leave people feeling empty and unsettled.