I am going to play devil’s advocate and say you can watch porn to self harm. I did this too, only I would find stuff that would make me legitimately uncomfortable, like videos of wives and girlfriends cheating, and force myself to watch it for hours on end. The more depressed I was, the more of it I’d watch and, frequently, I’d leave in a very bad state. The truth is, I was seriously considering suicide at this point and the porn, something that had been a cheap release for me, had now become a way to hurt myself like everything else.

The psychology of this was simple. I had no girlfriend (much like your boyfriend), and really wanted one. The problem was I didn’t feel like I’d be enough and these hypothetical relationships would only ever end with her cheating on me. Basically, the porn was a way to live force that sense of jealousy and vulnerability on myself. It was a reminder of why I couldn’t have a girlfriend, why I was better alone, and, towards the end, just better off dead. I am in no way turned on by the notion of my hypothetical spouse’s infidelity, it really was just a way to hurt myself. I never cut, I never hurt myself overtly physically, but I did do my best to self-destruct in ways I could easily hide.

Now, I’m not saying this is the case for your boyfriend, but this is my personal experience. If you have any further questions, feel free to ask.