ahhh what to do??

Hi! My bf and I are in college. He invited me to this event next Sunday. It's a day drinking/festival/concert thing. For some reason he mentioned as a plus one event (idk if that was trying to guilt me in to going or what). I'm not a bigger drinker and neither is he but he likes the social scene. The thing is if I have to go he would have to drive me back at night since my car is not reliable enough for the 2 hour ride. He did invite me so I took that as he rather spend time with me then his friends/drinking. But on the other hand the main part of this is the concert at night which if I go I would have to miss. Should I just tel him to have fun and not worry about me or what? I don't want to be a drag and want him to have fun. What would you do?