True Birch, but on the other hand, he may be the way he is in response to her rejection. Guys getting drunk and wallowing themselves in other girls to make the pain go away isn't unheard of, I'm not validating that it is a good excuse, simply that it does occur often. Similar to the cliche "depressed heartbroken so stuff themselves with chocolate/ice cream girls after a break up" version. This is all assuming of course, that he genuinely cared and loved you.
However, I'm not sure what he is doing talking to underaged girls anyway if he can get girls to sleep with in every city.
Lil lady, I know that he has been a great friend to you for some time, but if possible, I'd like for you to think this through and ponder if perhaps you are feeling this "love" only because you have lost him. Emotions rise and change under certain circumstances of events, desperation and fear are some of them. It's some psychological process where fear, etc can alter your perceptions of attraction and such. If you've ever witnessed a movie where the world is about to end or somebody felt certain to die, they suddenly get attracted to each other last minute and have sex or something, thats where they got the idea from. You certainly miss him it seems, but are you sure its love, your realization that he may not be with you anymore and you missing him could fool you into believing that you do.
Truthfully, whether or not you really do love him, I think there is a small chance of this relationship working out if you two made up and got together. You are now what, 16? He is about 30. You are still so very young, you have so much more to see, so many opportunities. He is a musician that requires him to be a nomad. If you have any dreams for the future in terms of career and such, you will have to obliterate pretty much all of them if you wish to be with him, because it would probably only work out if you followed him everywhere with his band. Otherwise, what, will you stay at home till he comes back from some far away city (remember he seems to be able to sleep with girls very well), and be happy with that for the rest of your life?
I think you should move on and seek somebody more compatible. Good luck, keep us updated!