There was a Prince Consort not so long ago... Victoria, being a queen in her own right, could not then marry and make Albert king, as he would have become superior (stupid mysoginistic rule that means the male is always first in line, even if there are older sisters). It's unlikely anyone would accept Camilla as queen, particularly with her divorced status, so consort is an acceptable alternative.

And as for making up titles, it's not a new thing. The Queen Mother was so horrified at the prospect of being the Queen Dowager (her correct title after the death of her husband), she made them come up with something she could live with.

LTS