She's a relatively new model who signs with a powerful agency. He works for some secretive three-letter organization that's investigating the very same agency. She falls into sexual decadency, then so does he, and it eventually breaks up their marriage. If I recall correctly, the final chapter ends with them considering a reconciliation.
I'm also trying to recall a vaguely similar story of a wife...eventually multiple wives...seduced by sex and drugs and whatnot by an agency. The climax is either several or a bunch of the husbands getting together and storming a retreat or ranch of some sort to "rescue" their wives.