The intention may be completely caring. They want to know whether what they are doing feels good, or perhaps they are physically tired and trying to understand where things are going.
But the brain has just received a new task: evaluate progress.
How close am I? Why hasn’t it happened yet? How much time has passed? Are they tired? Are they waiting? Is something wrong with me again?
A few seconds earlier, attention was inside sensation. Now part of it is occupied with monitoring and evaluation.
This can be especially noticeable for people who need sustained attention to arousal in order to orgasm: one stray thought can suddenly launch an entire staff meeting inside the head.
That is why there can be a bigger difference than it seems between “Does this feel good?” and “Are you nearly there?” The first asks about what feels good right now. The second can accidentally remind someone that the experience is expected to produce a result.