How do you break up with someone?

To make a long story short, we’ve been dating for eight months now. The first two months of our relationship were very unhealthy and I was going to break up with him because of his behavior. He started working on changing and while I am happy for him, it won’t help the fact that we are just incompatible together. We are at different maturity levels; he is not immature in a traditional sense, but he’s very stunted when it comes to emotional maturity. His social skills are also not the best and his inability to communicate and listen like a normal individual has really made it hard to want to stay with him in the long-term. He may be fine with it\*, but I can tell it’s something I wouldn’t be happy with.

I just don’t want to wait for him to catch up. I think he has a good foundation for continuing growth on his own, and I want to date that mature version of him, but I don’t want to date potential because I don’t want to be miserable waiting for someone to change. I want to keep him in my life, I just can’t bring myself to stay with this current version of him because I feel like it’s hindering my growth, as well. Is there anyway to do something like that, where you go back to the pre-dating “getting to know each other” period and aim for a fresh start, or is this just something that should end? And, if it’s the latter, then how do you break up with someone?

\*For more context: This is my (20F) first relationship. This is his (21M) fifth one. He says this is the first healthy relationship he’s ever had, so he isn’t going to see a problem with what I’m saying since he benefits more from being in this relationship than I do.

Edit: Some more context I feel would probably help. We started dating three days after we first spoke to each other (which I was not crazy about). We were not friends beforehand. We didn’t have a honeymoon period.