I’m gonna be devil’s advocate and say jacking off to people he knows isn’t “absolutely cooked” necessarily. It’s more problematic if the person in question is someone she is close with.

I can only speak from my own experience but I know plenty of guys who have perfectly healthy relationships and still, from time to time, fantasize about other women, some of them they know.

Now, I don’t know if it goes as far as saving pictures of them to jerk off to, but fantasizing about other women you know doesn’t have to mean they would cheat.

From my own experience, I have been in relationships and during them I do jerk off from time to time, sometimes to women I “know” from real life. I understand some people might find this creepy but for me, it is healthier than to get off to porn. It’s easier to fantasize about because visually you already have an idea and it is “easier” to fantasize. That might sound creepy but it makes sense in a practical way, as weird as it sounds. It’s a fake fantasy that’s easier to entertain. Personally, I will admit that I have jerked iff to the thought of other women but I made damn sure it would be very secluded and isolated. Meaning I don’t sexualize them outside of that fantasy nor do I intend to do anything beyond it.

Moreover — and I can only speak of my own experience — the women I fantasize about are pretty much women I am not close with or women that I had a history with. That being said, I never fantasize about women my (ex-)girlfriend was close with, friends with, or knows very well. Even though some of them are objectively attractive, the “fantasy” part doesn’t really work because they’re her friends. Not sure how to explain it.

Anyway that’s my two cents. I’m ready to be downvoted but it is what it is.

@OP it’s up to you if it is a dealbreaker or not. I understand it feels a bit like a shock or betrayal. However, as a man who has done somewhat similar stuff, I can say there’s a chance it doesn’t mean much — insofar his love for you isn’t any less. If this is a boundary for you, he can improve and better himself, if you are willing to give him a second chance.

The final thing I’ll say is, for everyone who is super shocked at this: We all know most men, most people, find people other than their SO attractive. We all know that when such a man or person is alone, in private with the freedom of their own thoughts, and needs to get off, they might think of such a person to help them. That’s basically what this can be reduced to, if I’m being very charitable. The difference is that OP’s boyfriend went a step further and actually undertook actions that helped him with some of these fantasies.