Very interesting post I think. I have never had an experience like this before but the way you put it makes it sound really cool. I should put on my goals list to find my dream guide, as I think it would be a great thing to have a companion throughout all of my dreams.

To help answer your question, I think that "girl" might be the other side of yourself. Since she cannot be unsummoned, it must be another part of your mind that is stronger than your conscious will power. That is the only logical explanation I can come up with...