He lied and told you that the door to his secret sexual basement was sealed, but it's not. He might even have wanted to never look at porn again and believed himself when he said he really meant it, that he was done this time.
IMO, the expanded access to porn that the internet facilitated is one of the worst things that happened to our society in the last thirty years. I believe that most men use it, and most users hide and/or lie about the frequency of their usage. I'm also of the opinion that setting a boundary about a partner's porn usage is almost always going to backfire.
From Psychology Today: "Using a set of metrics that includes indicators of monthly unique visitors as well as monthly pageviews, the authors found that the top three pornography sites are more highly ranked than the most well-known household name sites (Amazon, Netflix, Yahoo) as well as those that are the most up and coming (TikTok, OpenAI/ChatGPT, Zoom).Exactly how great is this disparity? In a word, huge. Xvideos, the top-ranked pornography site, had 700,000,000 more total visits than Amazon and 900,000,000, 1,100,000,000, 1,300,000,000, 1,500,000,000, and 1,800,000,000 more total visits than TikTok, OpenAI, LinkedIn, Netflix, and The Weather Channel, respectively."
I don't know about you, but I find that stunning. That's what we're up against.