Well, during romance talks with your companion, it plays one of a group from the Romance soundtrack, once you leave your ship/cantina it stops immediately, if your just talking about music in general, don't know... Guess that music is just for that specific area.

Just wanted to give you guys n' girls a link to listen to the SWTOR Romance music. In my opinion, I thought it was... just amazing, very, very beautiful music. Gave me Goose bumps at some parts of the songs. Hope you like it, Enjoy http://www.youtube.com/watch?v=CTqmQHOv-Z0

There's also one that drops on Hoth on the Herioc 4, Gammorrean Raiders, where you have to kill the invincible Horde.