Until a few years ago, I had a neighbor named Donna. Widowed well before she was ready, she plodded on, alone in her leaky house, unread mail and remembrances piling up in dusty corners. We invited her to holiday meals, cared for her dying cat, and, when the 2007 wildfire forced our town’s evacuation, she came with us, enjoying a prolonged pajama party in a small, borrowed apartment, raucous with four women.