Clients come from need, recognition, and relationship. It's easy to overthink why a client doesn't return, like we used to ruminate over why the other children don't like me.
We are not meant to mesh or get along with everyone. Frankly, how boring would the world be if that were true? We wouldn't ever find "our people"!
I'm sure you value those who return enough to feel like family. Stay open to new relationships, seek out and be vulnerable to the new, and don't dwell on the ones that move on, other than honestly reflecting on why. If your lucky, asking the ones that leave to let you know why without fear of hearing the truth will, on rare occasions, be honest and helpful.