Issur is not the main issue
Yaakov asks Dov:
If someone (who is likely an addict) asks us about the "issur" in these things, how do you suggest we steer them to the real issues?
Try to see if they are really convinced that if they could be convinced it were assur, they'd stop. Once they make it clear that they don't really believe they'd stop if they found out it were assur, your job is to help them admit why they are really concerned about their behavior. Sometimes it is because of punishment from G-d. Usually, they will admit it is because it makes them feel like idiots that they are impulsive, they are terrified of getting caught and know they eventually will, and other such real things. The teenagers usually still feel their main concern is that G-d will kill them, etc.
They need a good Rav - but if they are asked and admit they already have seen therapists for 'other issues', our job is to ask them why they never discussed this porn/sex matter with the shrink and are only coming to us about it. Often this is the case. If so, they usually admit they were too ashamed to tell the shrink and it is our duty to help them open up to the shrink they have a relationship with. Sometimes they say the reason they hid it (or sometimes just the full extent of it) was: "My shrink is a goy and he or she would just tell me that it's alright to do that stuff," - but they do not know that for sure, so it is time they found out. If the therapist really does say that masturbation is wonderful, then usually what happened was that they just told the shrink half the facts, as in "I masturbate and look at porn sometimes a bit, yeah," and that's a lie. They misrepresented the truth and didn't admit to the shrink all the pain and details and facts the way they just admitted it all to us. We need to help them admit they have been hiding from their own therapist and wasting their time and money even about all the other issues as well. And that if they do not trust their therapist, the therapy has been a joke, to some degree. But the truth usually isn't really the 'goy' business at all. The truth almost always boils down to this: Their therapist already knew them, has a real person relationship with them, and that made opening up about the truth much too embarrassing for them to do. Therefore they are on GYE hiding behind a mystery name and being 'honest' with us. It's useless, of course. They are playing, fooling themselves and playing the 'religion card'. But telling them that fact is very dangerous. Still, I tell them just that - but very slowly and in a way that they basically hang themselves with their own rope, as usual.
These are some of the threads I go on w these folks. Each one is different, each takes a different turn, but most fall into some of these directions. This is the start, of course. The next part is talking things over. After that comes advice on where to go from here. Usually, I give options, sometimes advice.
Hope that was helpful!