Why did Kaiser Wilhelm II abdicate?

There was a revolution in Germany in November 1918 and the army did nothing to uphold the monarchy, so Kaiser Wilhelm II fled to the Netherlands and abdicated.

To fill it out the answer, the facts of the abdication are pretty much like this:
The abdication of Kaiser Wilhelm II was announced by the German government on November 9, 1918, two days before the armistice that ended the war. Woodrow Wilson, the US President, had declared there would be no negotiation with the Kaiser and Germany was desparate to end the war. The announcement of the abdication was made regardless of Wilhelm's wishes. Even his staunch ally, von Hindenberg, succumbed to its inevitability.
Having, in many ways, instigated the war, as it went on its sorry way, he became increasingly relegated to a figure-head role, though quite a meddlesome one. By the last phases of the war Wilhelm himself was almost totally isolated, with no power base. Elite troops of the army mutinied in November 1918 and there were fears of a Soviet-style revolution in Germany. Wilhelm escaped into exile in Holland, a neutral state throughout the war, a day after the abdication. The Dutch refused to hand him over to the Allies for trial as a war criminal and he died there in 1941.