Have you ever become friends with a client?

New therapist here. I KNOW it’s not ethical (for a multitude of reasons) but I’m genuinely curious…Because of the nature of human connection, has anyone here ever wanted to, or even did end up staying in touch with a client after working with them, or developing a friendship? If so, what happened?

For reference- I’m not currently tempted to do this. I just started realizing that if I have a long career in this field that naturally along the way this might come up at some point and I want to be prepared.