The shrinking world

The reason this is hard to see from the inside is that you have lost the instruments you would use to see it.

Reality gets checked against other people. When you had six people in your life, one of them would have said, at some point, that what you just described was not normal. With one person left, and that person kept at a distance, there is nobody to check against. Your own judgement becomes the only instrument, and your own judgement is the thing that has been worked on hardest.

This is why one person outside the loop who believes you changes more than any amount of thinking on your own. Not because they solve anything. Because they give you back a second instrument.