I'm seeing someone who is in a band, and I know what you are saying. It's tough when everyone is sitting around talking about music (the writing aspect, not just what bands they're listening to at the moment) and feeling almost out of place because you can't fully relate. Then comes in the practicing, playing shows, recording, etc etc. My boyfriend's band is very dedicated and all, but because most of the guys are still going to college and working to pay rent, it hasn't consumed their lives entirely - yet.
I don't go to every show, waiting around for him to be free so we can talk, but I support them and help them out in any way possible. But I also have my own life and everything that everyone else has said. It's great that you're trying to learn music yourself, which shows that you are committed to her and want to make an effort. But you're going to have to work at it (both sides, not just one or the other). The truth is, love isn't the only thing that keeps relationships working. If you both try to make time for each other (maybe one night a week make dinner together and just enjoy the time to yourselves, or whatever) and be supportive, understanding, and compromise, then it will all be ok.
I think I wrote too much.
Good luck redsock!!