I agree with kaliope. Except...

IF you value this relationship, and you don't want to end it, there must be some reason. Could it be that you are not only holding back your emotions, but also holding back your true self?

I suggest taking her to the music festival. If you truly aren't going to do anything "wrong", like cheating on her, or hitting on other girls, or heavy drug use, or whatever it might be that you would want to hide from her, then you should include her. If she doesn't like the "real you" then you will argue afterwards, and it will all fall apart, which is fine. BUT, if she totally digs it all, then THIS girl, the girl you ALREADY have, may just actually BE the girl that you sometimes wish that she was!

You aren't giving her a fair shake at it. (maybe). Don't throw a relationship away just because you don't want to include her in your other personality, while meanwhile you look at other girls that jive with your other personality.

Whatever you do, do NOT babysit her. She is a big girl. As long as you aren't being bad to her, her feelings are her own.

You do NOT want a relationship that feels like a "ball and chain". Either include her and make it work, or get out of the relationship.

In my humble opinion.