Had To Let A Client Go Today

So I had a client we will just call Bob. Bob was a dentist and he decided that he wanted a new website and SEO done for this business. I agreed to help him out and we had closed on a price after some time negotiating. I told Bob that SEO wouldn't happen overnight and in an industry that so competitive it could take some time to see results to which he confirmed he understood. Time went by and Things were great for a while and once I finished the site he loved it. I started the SEO and after one month the panic set in Bob had messaged me something along the lines of "Hey I'm not seeing my site on the first page what's happening" now this wasn't the first time and wouldn't be the last time he did this. I assured him it could take anywhere from 3-6 months, but two weeks later he had continued with the same text and this time a little more angry. I reassured him again and thinks continued but after 2 months Bob messaged me saying that it was time to cut out partnership and that he would go somewhere cheaper for SEO especially if I wasn't providing results. I decided it wasn't even worth it to argue and just let him go. Moral of the story.... don't compromise your business or health for a customer who won't listen