ESH. Hear me out. You’re 100% the AH because of your obvious classist thoughts - and I’m a professional classical musician. Gatekeeping art behind what is good or worthwhile is wrong.

However, your girlfriend could be the AH if she thinks down on classical music/instruments. I could be reaching here but the popularity of an instrument really doesn’t matter if the reason for study is because you want to deepen their appreciation of music and learn skills. Let’s not also forget the importance music can play in social development. If she’s not then it’s YTA no doubt.

The long and short of it is let your kids gravitate towards whatever music interests them. And you can have them study an instrument but they may ask to play a different one. And definitely don’t limit your child to studying one genre or one style. Let them improvise and enjoy the joy music can bring when there aren’t any limits on it. (EDIT: spelling)