BERLIN — Most flight attendants have a tale to tell of long-distance relationships, but this one has a happy ending that’s enchanted legions of social media users worldwide. It all began in February, when a Lufthansa employee flew to Argentina and encountered a stray dog outside her hotel. “I stroked him, gave him some food and we took a walk through the streets,” Olivia Sievers said in an email Friday. “I had a feeling that this dog was looking for a human friend.” Sure enough, he found one in Sievers. “I gave Rubio my attention and my time,” she said. On Sievers’ next trip to Buenos Aires her four-legged friend was again waiting at the hotel. And again the next time after that. The long-time animal rights activist brought him flea and tick medication and even attempted to find a home for him in Buenos Aires, but he’d clearly lost [...]