Any sufferers of delayed ejaculation (DE) willing to share experiences and advice?

I am not a sufferer but my fiancé is. This is one of the most under researched areas of male ED and that's not just the porn induced type of DE. I've read everything and it really needs to be studied more. My fiancé has only been able to ejaculate with me once from a blow job when we were on a three week holiday and he could not PMO. He can stay hard for hours. He can masturbate in front of me but even then it takes a long time. He can do it alone to porn in seconds. He's doing a reboot now but I'm pretty sure he's not convinced it is the porn so not sure it will work. This kills a relationship and many men end up just using porn and solo sex because it's the only way they can get off and the women feel neglected and the relationship ends. I think if you rule out every physical cause and you are a heavy port user and pmo a lot you should consider it as a potential cause. My fiancé says that he just can't get to the point of orgasm and he starts to have a numbing sensation which we learned is not physical. Being with me no matter what I do never gets him above say a 5 on a scale of 1-10 with 10 being an orgasm.