Fear of Heeling
Can''t help you much there; sorry. I have observed that fear is often irrational, and it is very difficult to logically convince someone that his/her fear is not justified.
When I got my wife into a situation she disliked (or feared), I often heard the familiar, "you owe me a BIG piece of jewlery for this, buddy!" Fortunately, she was only partially serious. I now tell her we can''t afford trinkets and worthless (i.e. non-boat) stuff so that I can afford to buy us a boat that will make her more comfortable.
Good luck helping your wife over her fears.