I'm gonna go out on a limb here: if your idea of a great proposal is to do it at a death metal concert, I'm going to venture to say you're not mature enough for marriage.
If you need a state and/or religion sanctioned ceremony to bond you to another person you want to spend your life with, you're probably not mature enough for marriage.
I've worked a few music venues in my day. There was all kinds of depressing shit like this. A group of three ladies came to a dance party one night to celebrate one of their birthdays. The room capacity was 600 and they were the only people there. (the venue closed a few months later)