German President Horst Kohler's resignation on Monday came as a shock to Germany. But it was long clear that he was unhappy in his job, and his departure will allow a fresh start for the office of the president.

As German President Horst Kohler announced his resignation on TV, he appeared to be close to tears. Could the moment have been any stranger? What a surreal minute in German history. It was as if time in politics stood still for a moment. The entire country held its breath.

The moment of shock must now be followed by sober analysis. It exposes a harsh but simple truth: Horst Kohler and the office of president didn't fit together. They weren't made for each other. He had also noticed that - long before Monday. It made him an unhappy president, and it's why the criticism over his comments on Afghanistan a week ago led him to step down. He must have been deeply hurt that no one from the governing parties came to his aid, to support him or defend him in the controversy. Not even Chancellor Angela Merkel.

The man and the office just didn't fit. The form his resignation took - this feeling of being offended, this mix of self-pity and anger towards others, confirms this. A German federal president doesn't resign because - within the scope of a normal process of democratic debate - he is criticized. That's an overreaction that doesn't befit the office.