Did he agree not to look at it because HE agrees with it? Or because it would make you happy?

Because there are plenty of people who believe porn, erotic literature, wtv is just a part of exploring and enjoying sex. It doesn't mean he is cheating.

So, it seems like you disagree about porn, and I suppose it's application/utility.

So if you sit down and find out WHY he likes it... you might feel better. You might not, since I assume you'll find out he actually does like it, would like to view it, and didn't just for you.

Basically, I wonder:

When you had the talk and the agreement, who led the talk? Who brought it up? Was this your idea or his?

There is no harm in it, and if it worked for you/him/your couple then it wouldn't be a problem at ALL.

But a bit of digging to see how you got here might ne necessary. Once you know how he truly feels about it, you can reestablish boundaries that work for thw two of you.

You might need some outside help for it though, if you are mad at him or find out you both disagree on the topic.