If you are middle-aged, there is a fairly good chance you are alone. As people have left their home towns to pursue their careers, as record numbers of baby boomers have joined what researchers call the “Gray Divorce Revolution,” more than a third of adults between ages 45 and 65 are fending for themselves. For them – for everyone, really — friends are no longer a luxury. They are a lifeline. This is more than a psychological phenomenon, says James Coan, a UVA psychology professor who directs the Virginia Affective Neuroscience Laboratory. Friends share the burden of li...