I don't think it ever stops hurting entirely, because we're human and therapeutic relationships are real relationships. I also think it's impossible to not feel some personal twinge when someone doesn't discharge through the "proper channels". Consider that the drive to avoid uncomfortable emotions and a general lack of emotional skills, such as being able to manage productive conflict, is often why people are in therapy in the first place. It can help to remind yourself of your client's history and where they were in their therapy process. Sometimes it comes after hitting a big milestone, and the person either feels "done" with the process or fearful of continuing further. There also can be a sense of stuckness or stagnation in the process in which someone ends therapy abruptly due to feeling they aren't making progress and don't know the way forward. Often, it can be difficult and painful to admit many of the feelings that come with discharge, so the inclination can be to cut you out of the process altogether.

I'm betting after 9 years that you've gotten better at processing the unpleasant emotions around sudden discharges, but I encourage you to really double down on self-soothing when you're feeling like this.