What is it about drummers? Honestly your description fits just about every drummer I have ever known in my life, and most I've heard about. Then again, I've been trying to pick up drums since losing motor skills in my left hand (more or less needed for Bass lest I start playing lefty...)
Okay, weird coincidences aside you most likely need to corner the boy and force him to talk about things. What settling down entails (you can be settled and stay part of the band. It takes some juggling sometimes, and can be stressful, but if it isn't the band it's something else, so why not let it be the band?)
You also need to think about yourself a bit. Why do you wonder if some other girl is more his type? has he displayed a wandering eye? Is there something in your past that makes you insecure in this area (as a man with long term issues, I have a lot of this one myself)?
In the end it comes down to what you want and how far you are willing to do/put up with/wait/etc... to get it. Remember, all relationships involve yourself and someone else, and you'll have a hard time ditching yourself at the bar. Believe me, I tried the fake emergency phone call and everything, but never once fell for it.