Pittsburgh's dominant health insurance company and its largest healthcare provider are, essentially, getting a divorce. For decades, Highmark Blue Cross/Blue Shield and University of Pittsburgh Medical Centerworked together. But as the line between insurance companies and health care providers across the country blurs, these longtime allies are venturing into each other's business and becoming competitors. In the process, patients can get caught in the middle. Day-care worker Gail Jameson has Highmark insurance and she's been going to the same UPMC medical office for more than 20 years. "I could go in and just stop in if I needed to because it's close to my work," Jameson says. "I go past it every day."