Place it at the end of a scene, after the awkward moment has already played out, so it closes the bit instead of starting it. Pair it with Dun Dun Dun just before the reveal, then let this clip deliver the exit on its own.
About this sound
This is a short spoken line, lasting about 2.7 seconds, in which a voice quietly says it does not want to be around anymore, trailing off as if the thought is unfinished. It feels weary, awkward and withdrawn, like someone stepping back from a room without making a scene. The low, flat delivery makes the discomfort land gently rather than loudly.