Question about this situation, friend invited, and then made the decision for me....?

I hate it when the person I am with looks and acts like they aren't having fun.. so, might I suggest that if you don't want to go you should possibly see what you can do about finding someone else for him to go with. You know..someone who really wants to be there :) Not knowing anything about the dynamics of your relationship with this guy it's hard to say whether this would be a deal breaker and he'd never ask you to do another thing for the rest of your life or if he'd be cool with it. But, the sooner you make up your mind the better ... because it might take a minute to find someone else if you do decide to back out.