I have not heard many forum posters mentioning trying her intensive. In this thread, BobbiJo signed up for one, but unfortunately, her husband bailed. Some promise an easy D if it doesn't work in exchange for their soon-to-be-ex attending what they see as a "last resort" intervention.
I have heard several forum posters mentioning Retrouvaille. My recollection is that Curtis went and it did not help, AnotherStander learned valuable tools but it didn't save his marriage.
Heartbroken credited it with saving her marriage. Sara says 50%+ success rate. hope and eldiemarie also said it helped, but to go into it with the mindset of IT HELPING FIX YOU instead of the mindset of IT HELPING FIX YOUR SPOUSE. These posters have long since moved on.
Anyway, some leads for you. I have no personal experience.