I can see why you are not happy. I would go with something lighter in the same color family on the paint chart. You could also go white if you wanted to create a stark contrast between the two spaces. However, I would stay in the same color family (but lighter) if I were you.

In an empty space with no context, this is totally subjective. There's nothing inherently wrong with dark brown and lighter blue, if the decor that is loaded in supports this color combo. However, I can't tell if you are down on blue in general, or just the way this particular blue turned out. You could use other accent colors (again, depending on how your plan to decorate that general area) including orange, rust, gold, grass green, even violet or lavender. Or fall back on safe beige. I would also consider painting the niche around your window the same color as the nook. It seems a bit stark white against the dark walls.