Define Long Distance. Shes Scared Of A Ld Relationship.?

Ok, first off, please define what type of drive distance you think qualifies as a long distance relationship. (hours, not miles please)
This girl and I have been friends for a long time, and are infact best of friends now. We tell eachother everything, and are open about the fact that we both like eachother, but we dont talk about that fact often. She gets all quiet and says long distance relationships dont work.
Then, yesterday over aim she vented about everything going wrong at the moment and then went on to say that she would absoloutley love to date me, but she doesnt thing long distance ever works out. She has MAJOR trust issues, even with me to an extent. She said that if we ever ended up at the same college, she would date me in a heartbeat, but, again, she isnt sure if I could be faitlful, and she said she doesnt know if she could. She also stated that she doesnt want to risk our friendship. ***more details in a second***