It sounds like porn addiction? I've heard about people who get so into porn, they just don't want sex with their partner anymore. I'm really sorry I'd be really upset, too.
I know exactly how you feel. My ex-h preferred porn over me. It hurts. It hurts a lot. Be honest with him, he needs to hear how you feel and you deserve an explanation.
I am sorry things are strained and you're feeling badly. It sucks and it's a shitty position to be in.
Remember you can rub one out too.
This seems helpful!
Sarcasm? Look, I am sorry that she's suffering, but things can improve. That is important to know. And she can help herself sexually. I think everyone else's advice to talk about it, is very helpful too.
Sometimes when a person is in a situation and it's painful, it can feel very static and immovable and like the present will go on forever, but things change and improvement is a possibility.
You might not like my contribution, but whatevs. I am trying to help.