How to tell frequent client that I will no longer be dog sitting for Rover?

My Rover sitter left the platform once, and I thought he handled it beautifully. He let me know in advance, and then told me had met with three other sitters on Rover to discuss referring his clients. Knowing that he vetted them in advance was awesome. I looked at their profiles and picked the one that looked the most suitable for my pup.

Then,the old sitter even came to the meet and greet with the new sitter. He explained how my dog behaved when he was in the home, any weird things I might forget to mention, etc. This was the kind of "above and beyond" that made him so excellent a sitter. I even wrote a recommendation letter for his trade school application to let him know how his service meant to me (and my pup, Jango!).