I actually believe that when people are frustrated and it's emotional or sentimental and they say exhaustedly "I don't know", what they really mean to say is "I know, but I don't like it and thus refuse to acknowledge".  But today I am in emotional turmoil and trying to do what is "best for me" but I've got boyfriend fog covering me.  Yesterday I was really clear about what to do and had decided to take a breather. But after talking and sleeping last night at our place.  I cannot make a decision.  Wading through grayness. What happened to the damn ROAD ?!
Example: 
I don't know factual
 Question:  Who won the world series? (a factual and existing piece of information)
  Response: I don't know
I don't know emotional
 Question:  How do you feel? (changing like the weather, but still possible to clearly identify at any given moment)
   Response:  I don't know (a lie)
I don't know of today
  Question:  What do you want to do?
    Response:  I don't know (Is it possible to do 3 things at once?)