Boyfriend doesn’t like the idea of marriage

My boyfriend of 3 years, has grown up in a religious home so he grew up thinking marriage is a right away thing in only a couple years of dating. I am not so I told him I am in no rush to get married and that I would prefer to wait till we’re not so young, but not everything has changed. I’m worried that me pushing “my way” on the marriage topic has turned his opinions on it because now I am the one who wants to get married and he does not. It’s not that he doesn’t want to marry me, he just doesn’t want marriage in general. Which sucks

I’m at a loss of what to do, we have a good relationship and I love him more than anyone. I know it’s stupid to say I don’t want anyone else if it can’t be him and that I can’t take the heartbreak that would bring on but im not only losing him, I’d be losing my stepson as well that I’ve been a mom to since his birth. I know marriage is not that big of deal, to me anyway, we already basically are since we’ve lived together for a couple years and do everything together but im just having a really hard time knowing if I rather stay with the love of my life and maybe he’ll change his views in the future because he is known for changing his opinions often enough, or if marriage is important enough to me to think otherwise.

He has been very good during these discussions, telling me he only wants to be fair to me and knows what I deserve but just the thought of it turns me into a wreck because I can’t fathom not having my best friend with me. I know it’s not his fault I don’t like his opinion but it hasn’t stopped me from feeling like shit at the thought of not being with him