Why? Germany's the country that can absorb default of the Greek loans. Don't they mostly control the EU printing presses?
Outside the box, but might it be wise for Germany to back out and do comparatively better than everyone else if other European economies are threatened?
Germany could indeed back out, but they are heavily dependent on exports to other EU countries and it would hurt their economy. It's a crazy system: Germany is lending money to Greece, Spain, Italy, France so the people in those countries can buy products from Germany and keep the German economy going.
Germany and France have fought three great wars to build a United Europe, they will not give it up