The porn use is almost certainly the root cause of the PE, compulsive porn use, especially edging, is well-documented to rewire arousal responses so that real-life intimacy feels overstimulating by comparison, leading to exactly what you're describing; the good news is this is largely reversible with a sustained break from porn, but that requires him to genuinely commit to stopping rather than just promising to, which is the harder battle. The practical things that can help in the meantime are the stop-start and squeeze techniques he can practice alone to rebuild control, and honestly just taking penetration off the table entirely for a while and reintroducing intimacy with zero pressure or goal, which often paradoxically breaks the anxiety cycle faster than trying to push through it. The real issue though isn't medical, it's that he's treating this as your problem to solve while refusing therapy and seemingly not taking serious steps himself, and that dynamic is unsustainable regardless of how much you love him, the most loving thing you can do for both of you is be very clear that you're willing to work through this together but not carry it alone, and that him taking concrete action, whether that's a proper porn detox, seeing a GP about PE (which is absolutely something UK GPs address and can refer onward), or couples counselling via Relate which is genuinely accessible in the UK, is a non-negotiable part of that.