I was in similar shoes at one point. In that I was resistant to his suggestions but implemented them after we broke up.
Why? Well I realized he was right, and that my refusal to even try therapy is what lead to our break up. That I had to try something different, because my methods were obviously not working, i was finally ready for a solution, relationship or no relationship.
I'm not sure why an "I admit I was stubborn and wrong and I'm finally taking your advice because you have my best interests at heart" would not be enough for your bf...(?)
Part of the reason my bf and I were able to reconcile was because he witnessed me trying to improve myself, and once we got back together, this translated into trying to improve / strengthen our relationship as well.
I'm not quite sure what your bf's beef is, because in all honesty it just seems quite childish to be "put off".