<human>: Currently I'm in law school.  A girl I sit next to (friends for about 1.5 years now), and always enjoy her company has become a really nice casual friend.  We haven't hung out in a couple months and tonight she came over so we could have some beers and watch a movie.  I thought this was going to be completely plutonic as there has never been anything between us, not even flirting to my knowledge (but I am pretty dense).  

She came over in a fairly short skirt with red lipstick on, and was done up pretty nice.  Everything was going pretty nice but there was a conspicuous lack of the usual who we're dating talking.  It didn't really bother me because we had plenty else to bullshit about.  During the course of the movie it dawned on me that the close sitting, nice (short) skirt, and lipstick meant we were on a date.  When the topic of conversation went to music I immediately mentioned how bad of taste my current lady I'm dating has in music (I wouldn't say she is my GF yet, but I would say her taste in music is awful).  When I mentioned this she let out an audible WTF type of sigh and the conversation stopped.  It was very awkward for the rest of the evening.  

How do I let her know that I really like her as a friend, but my interests and tastes lay elsewhere?  Can I keep her as a friend, or do I need to put in some distance (changing where I sit will be awkward, and everyone will know somethings up. Law school is worse than middle school as far as the rumor mill goes)?

Could you distill the essence of the text into 1-3 sentences?
<bot>: I have been friends with a lawschool classmate for the last 1.5 years.  She showed some interest tonight and I mentioned my GF to her dismay.  I would like to remain friends with her, but not go further.