Porn is something that has never bothered me. Like someone else said, it's just a fantasy. And I think it's something most men do, openly or in secret.
It doesn't mean he doesn't love you, or that you're not attractive, or second choice. It's just something he enjoys, something that is fun for him.
Do you not have fantasies that revolve around sex? (No need to answer that here, just ask yourself.)

I really don't think that a man who enjoys porn will ever quit. He might hide it and *say* he quit, but I really don't think he will. And I don't think you can make a man quit watching porn.

When I married my husband (we had only dated for three months prior to getting married) he thought he had to hide his porn too. I kept telling him it doesn't bother me, and he doesn't need to hide it. But it took a couple of years before it clicked with him that yes, it really doesn't bother me.

Maybe you could sit down calmly with your boyfriend and talk about it. Let him know how it makes you feel, calmly, without accusations, just "you watching porn and then having sex with me makes me feel like your second choice". And then give him the chance to explain what porn means to him. Why he watches it. And maybe you'll discover and understand that it has absolutely nothing to do with you. Maybe such a talk will make you feel better.

Have you ever tried watching some porn WITH him? (Again, no need to answer here.) That could be helpful too.

I hope this was just a little bit helpful. Good luck!