There are times in life when God Himself brings blindness, I think. Or maybe a better way to put it is “fog” because blindness carries with it moral undertones.
The fog comes to limit our vision and focus us on the day. Why? I suspect it’s to create a level of obedience and dependence in the day that cannot be done any other way (e.g. manna in the wilderness). It’s less of a challenge to obey today if you can see the hope of tomorrow.
The fog sits and sometimes does not clear for a long time.