Boyfriend Doesn’t want to get married at all

I just want your opinion ladies! So here’s a little back story of us. We have been together for 4 years on and off officially together a year. We are expecting our first child in November. I’ve always thought of getting married one day. I bring it up to every once in a while to see what he will say. Every time it’s no I don’t want to. I’ll even ask what about later in the future and it’s still a no. He never says why he doesn’t want to. It just bugs me. Any other ladies have any similar situations? Any suggestions? Opinion on why he might not want to?