Disclaimer: this is my own theory, based on my journey and things that I have read. There is a common pattern among testimonials on nofap.com: men that have checked themselves with a physician and have normal results in analysis of blood, heart, digestive system, etc. but still suffer unbearable anxiety and insomnia among others (these are the most common). I don't think this has to do with the dopaminergic system. Indulging with PMO for hours is so incredibly pleasant that everything else becomes annoying and uninteresting, even irritating. With time, our system adapts to that, gets used to the pleasant state --and wants more. Then what was the normal state turns into something unacceptable and disappointing --"disappointment" is synonymous with anxiety in the Thesaurus dictionary. Our body interprets what used to be normal as a threat, and hence activates the fight or flight mechanism, which switches off the immune system, keeps you alert (insomnia), causes you fear (anxiety and panic attacks), halts your digestive system (heartburn and nausea), etc. Although I didn't suffer from PIED, I would apply the same logic thereto: an ordinary relation is "boring" compared to PMO. Hence you don't get aroused by normal things. As I said, in my humble opinion this has nothing to do with dopamine. Dopamine is what makes you chase PMO, what makes you disregard other important things to attend your addiction, what makes you want to repeat and escalate more and more. In short, what makes you an addict. --- P.S: striking-through some parts where I don't really know enough to draw conclusions.