The MC is better trained to work with stubborn maital partners... its part of the job...
Going into a MC's office is tantamount to a negotiation... The MC if they are good will have the talent to talk to your H in a way that gets this into his head...
God MC's aren't just analysts, they are educators who know how to deal with "children with paycheques"
As long as your MC is a good one, they should be able to do this... That's what they do...
And if he is addicted, which I suspect he is, he is going to be very stubborn, ensure your MC is educated on infldelity as an addiction so they know what they are dealing with...