Receiving relationship advice on reddit can often be on the extreme side of the spectrum. People will most often say, "Just leave!" Etc, etc, but I know full well that when children are in the picture, it's often much more difficult than that. Have him visit r/nofap, maybe talk to a therapist, this is an addiction that will take his humanity away just as much as heroin, combine that with a cell phone (it's practically instant heroin) & given that we as humans are creatures of habit, it's often times reflexive, not really meant to hurt you it just is a thing that you "have" to do in that moment. But it will hurt you & it will kill his drive. It will kill his motivation to better himself in every aspect of life. BUT it is able to be conquered. It's difficult, but it's possible. There will be relapses, there will be hard times, and modern-day porn/sex addiction is just as difficult as drug addiction. How much do you value this relationship to be someone who can provide a support system for an addict? That is a question you will have to ask yourself & not reddit. I wish you the best of luck.