Porn is not nearly as serious a threat to the marriage...
Porn can cause a lot of tension and upset, but its not nearly as bad as an actual third party deliberately trying to derail your marital train...
It also depends on how bad the addiction is. If the H is going out to strip clubs with rowdy men and spending 1000 bucks a month on internet video's and phone sex then yes, I would say its time to ask some of his family to step in.
If its something much milder a private confrontation first is likely in order to determine if he IS willing to see a therapist about this and curb the behaviuor.
It's also harder to reverse expose porn use. With infidleity its a LOT easier to SELL "I'm in love and getting a divorce" than it is to sell "I'm hanging out on the internet at all hours of the night consuming porn and i enjoy it"
Part of the exposure tactic is to "cut the spouse off at the pass" so to speak since with infidelity the truth will come out eventually that you are pursuing someone.. Most cheaters will spread the news with their spin on it like above... If the WS exposes this first in a more painful light the WS' efforts to bring the truth out are foiled. The porn addict does not ever need to reveal what he's doing unlike the infidelity addict.
The other reason for exposing is to bring the family and friends into the marriage to support that marriage... much like a wedding when the community is invited to celebrate when things are well, when things are bad I too believe that bringing a smiliar group to gether to HOLD the marriage UP and keep it on both feet is essential. Hopefully the same people that were there to eat your wedding cake and dance to celebrate the good times will be willign to hop in and roll up their sleeves during the bad times too... if they aren't... Well you know who shouldn't have been invited to the wedding...
Different addictions are worse than others, and each addition has varying degrees of severity...
The biggest bonus to porn addiction is the fact that it is publically understood as a problem and is generally taboo - no one wants to admit they consume it regularly...
if Infidelity had this stigma it would be a much easier nut to crack
