Baritone Robert Orth, in town to play Don Alfonso in Portland Opera's production of Cosi Fan Tutte, is often away from home, appearing on stage. This week in Portland, someone asked him if he ever felt lonely being away from home so much. "When I started to travel," he replied, "yes, I did feel lonely. But now that I've spent thirty years on the road," he said with a whimsical tone that the dry words don't reflect, "I find myself endlessly fascinating."