Female led relationships discussion

For about a year, on and off, my partner and I have had an FLR, and while the sex/kink aspect is great FINALLY. There’s one issue: he is impossible to train and blatantly ignores my rules and orders almost daily. We’ve tried discussing it and using punishment for his disobedience (spanking and once I made him write lines), but it doesn’t seem to make him change. I feel discouraged and frustrated, which isn’t how a mostly fun kink should be, and definitely doesn’t inspire me to act like a good Mistress. What should I do? There are times when I just want to give up trying because it seems hopeless.