Issue confronted......calmly over dinner.
My hunch was correct.Her problem is 10% cost, 90% safety. The cost issue is not really a problem, I don't need to dwell on it here. The real issue is one of me falling uncontrollably from the sky one day. To be honest my wife has a "mild" fear of flying i.e she will get into a plane if she has to but would rather not. BTW, when I say plane I mean B737 A320 etc, so a Cessna 172 is definitely a non-runner.
On the plus side she actually made a point of learning exactly what is involved in gaining a PPL i.e the training program, instructor qualifications, ground school etc and what would be involved if I wanted to go further with my training, i.e CPL. These are questions that she was intentionally avoiding asking because she was hoping the whole thing would go away.
I have gone to lengths to explain to her how important my own life is to me and how I have no intention of putting myself in danger. In fact there was a eureka moment when she remembered how sticky I am when it comes to safety. As a landscape gardener I use potentially dangerous equipment on a daily basis and have spent quite a lot of money insuring I am properly qualified/trained in all of my machinery. It's not as if she didn't already know this but fortunately this has helped her to realize that she's not dealing with a flying maniac but a normal balanced person

who happens to love flying.
So we have agreed that I will not bore her with the technical details and that the option is open for her to join me on a lesson some day.

So long as I, for my part, be careful up there.