That's cute and all, but it's also pretty much what Google, Facebook, Apple, Microsoft, Spotify and all the other tech giants are doing when they're joyfully tracking what people are doing without their knowledge or consent.
Sure, still a bit weird tho. I mean what happens when OP is on a business trip and his gf seems to suddenly have a whole different taste in music in the morning? Could easily lead to misunderstandings...or not.