Intuition and Fear

My friend and I like to have what we call "couch therapy sessions." I don't really know how we came up with the name, they never really involve a couch. Typically we're walking around the neighborhood discussing men and relationships, intimacy and all other matters of the heart. The conversations are generally balanced between her practical approach to love and my...well...less practical, romanticized, idealistic approach.

Today we were talking about the relationship my friend had entered into with a man she had only known for a short period of time; completely out of character for her.  She was starting to feel that the relationship was moving too fast and beginning to doubt her decision.  She didn't know if she was just afraid because he was exposing parts of herself that she had kept hidden...or if her instinct was warning her to leave this man alone.

Though I was unable to offer much guidance, I could totally relate. I've been trying for some time to wrap my mind around the difference between intuition and fear.  They both seem to operate in similar fashion, coinciding closely with major decisions, transitions or changes in life. I haven't quite figured it out but here are some statements that ring true to me:

After making a decision based on intuition, you feel a sense of peace and "knowing."
Example: I wavered back and forth about quitting my "practical" job and moving to Chicago to pursue my passion for several months.  Finally, I submitted my resignation letter and immediately felt that I had made the right decision.

Intuition is often supported by other events and circumstances. 
Example:  After I committed to the decision to quit, opportunities and experiences presented themselves in ways that supported me.  I found the perfect temporary position that allowed me to develop my skills, build my confidence and meet powerful people in the industry.

Conversely, making a decision based on fear alone does not feel good. Even afterwards, you might continue to have negative feelings about it. 
Example: Thinking back to my relationship with the southern gent, I can now see that my decision to run away was based on my fear of intimacy. Even now, I question whether I made the "right" decision.

How do you define fear? intimacy? How do you tell the difference?