Feel insecure who my partner follows on Instagram

When I met my boyfriend, he used to follow models, only fans accounts. We've been together for 2 years, and still he follows some of the naked women. I don't have clue why he treats me like that. He told me several times that I am the only one. I feel so bad because of it. I really want to go on next step, but I don't know what should I do. I told him a lot of times about this situation and how I feel. But he does not do anything about it. Am I over reacting ?