The capture of the last white wizard, decolorized
True & Honest Fan
Its actually possible I got them confused. The Gods Themselves has been sitting on my shelf for years anyway, so that's still useful info.
I would consider the gods themselves worth rereading. If you're unsure, you can always just read the 2nd part only. First part is earth, second part is aliens, and third part is moon. I never liked the human parts much of that book, but the aliens bit is a proper good mindfuck... and it has interesting analogies with his own life.
In some sense it seems to be about his difficulties with married life as he seperated/tried again, published the book and then divorced and found a new partner that was much like one of the alien characters in some ways. A left em, so to speak.