Earth invaded for crop growing, small bands of survivors become cannibals

[pimpernel]

Despite the description I remember this as a darkly comic story. I think the main character is a mining engineer and because of this a group of survivors accept him, but eat his female companion who has no useful skills. It's a long time since I read this but if anyone can point me towards it I would be grateful.

[northernexposure]

OK, it sounds like Thomas Disch's The Genocides, except that I do not remember cannibalism.