In my case it's creeping boredom...
I'm not seeing anything in the political arena that I haven't seen a hundred times already. The bad news is my posts are developing the same syndrome: "Haven't I written this response about a dozen times already?" I'm tempted to number them, like the old "numbered joke" gag.
I don't think leaving completely is necessary--Eri's earlier idea of just sticking to the non-political areas here is still a good one.