Alright, looks like you've had some bad advice in this thread. That is troubling and an apology makes sense. I'll give a response and it's not my intention to come across as judgemental, I can only say what my own experience has been and put myself in his position.
Hopefully you aren't chased away entirely from this site because of one person that has a very particular view. I am not 100% against his view being militant myself regarding purity but I draw a line on some of that stuff because typically the "heart" of adultery is omitted. Someone that watches porn for 15 years and then gets married a virgin, are they really a virgin? Not in their heart, but physically sure. It's somewhat complicated sometimes the roots that are involved.
As to your question, as someone that is quite familiar with his struggle personally I do NOT think it is in ANY way appropriate for you to be helping him with this. If you were both married and it came out later that he struggled with it then sure, you could have deep sexual discussions in ways that as an unmarried virgin and a female seem kind of the opposite of pure. There are some rather scary traps that people have fallen into trying to get their significant other away from porn, YOU are NOT his standard or his guide to lead him away from that by yourself. It "could" work, but the risk is rather high to cross a line somewhere. Please don't take that risk when there are many other safer options that keep boundaries in place and are more effective.
I get that you want to help him, point him toward some help. It just seems to function better for that help to be another male (you mentioned your father). This is extremely important to discuss but I get that it's uncomfortable...do you have a pastor you can speak with?
Being near a woman and having an interest in a woman was always an extreme motivator to not give in to lust and my desire was even less and I was able to brute force a lot of it away and pray through just because there was a light at the end of the tunnel so to speak. To pursue purity with reckless abandon because maybe just maybe the finish line (and the ensuing "round 2") was in sight. So it seems strange to me that he is not motivated to discontinue use much more strongly as it is adultery in one's heart.
Does he have a computer? Does he have the internet? Is there any legitimate reason that he has to have the internet? Netflix, video games, social media, etc aren't legitimate reasons when the risk is pornography. Especially when you "know" it's a possibility.
Even cutting out porn isn't going to stop lustful thinking but it's a great start.
It could be he needs more specialized accountability besides just cutting off access, some can and some can't. I'll be honest that I cheated myself out of a lot of married time and experiences by doing it my way. Took way longer than it needed to.
A wife is NOT a fix for lust. Jesus and walking in holiness is the fix for lust. If that isn't taken care of before marriage there is most likely going to be some heartbreak. Maybe not divorce or anything, but a waywardness that is really sad
It's a struggle and it's a battle. I've known females to cut off all contact because they feel like they are being cheated on due to this. If you leave the door open with a "if you gain self-control/deliverance in this area then we can continue to court/date" mentality that's commendable. His freedom could be around the corner, but I do think he needs to involve someone else.
It's a heart issue more than anything. It could be that he's being tempted more strongly "because" of your interest, but still...based off my own experience he should want more than anything to be past this before being married because you can take a "fleshly" heart condition into marriage even if you are porn free. Being lust free is the goal, in all self-control.
It seems impossible sometimes to men in this place of sin, but Philippians 4:13