I think the why of it is that having advanced a painting so that it begins to please or satisfy me, I start being afraid of messing it up. I paint, but I am unconsciously holding back. Actually it's not that unconscious, which helps to maintain the general level of tension, but I am unable, at the time at least, to do anything about it.
I am not alone in encountering these bouts, from what I read and hear, it happens sometimes to artists - people creating. It is sometimes a part of the process.
Inevitably, I paint less well when I feel this way. Not that it is necessarily *bad* painting, but it is more of grind, maybe less "true".
Today all was well again, and I painted with quiet attention and confidence, feeling nourished as I painted.
Here is a detail of the painting from this evening (I worked a lot around the eye and nose):
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The full painting, still in process but feeling good:
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