I don't think they don't get along, I think it's more to do with Rosberg having to learn to cope with the pressures of leading the driver's championship, whereas Hamilton has been up there from the start of his F1 career. They both know each others strengths from racing together their whole driving careers, Rosberg knows he's never going to beat Hamilton on speed and has made a few mistakes when pushing for the win, which Hamilton has done as well (Canada 2011 springs to mind), but at the moment Hamilton is a more complete title winning driver over Rosberg, having had the pressure from his first season, whereas up until this season Rosberg has always languished outside the top 5.