Can he change?

So my boyfriend told me he had a subscribe to an only fans in his last relationship, for like 3 months. He has a specific kink that is very hard to find, cause it doesn’t even involve being naked, so he was looking for vids like that. I remembered his ex would send him vids of the things he liked so i asked him and he said he just wanted more, because his ex would never satisfy him to cum. I did explain that for me thats cheating cause you are still looking for other people to pleasure yourself while in a relationship which he said he understands and he does admit it was sleezy, but now i cant help but think that maybe even though I satisfy him, maybe he will want more. I asked him if he would get one now again and he said no and gave me his reasons , but it just scares me and worries me because he did it to his ex, he will eventually get tired of me and do it. Also am I in the wrong for not wanting him to be looking for that type of service, or on those websites?