Just to add a bit to Tammy's comment...
I moved to a new town when I started my MBA, and my whole life revolved around my classmates and the school's academic and social calendar, ESPECIALLY the first year. Admitedly, I was single, so I didn't have to concern myself with a significant other. But I can understand how your FI is getting caught up. Every day he's hearing the same things from his classmates - yes the party is dumb, but it will be fun! C'mon man, you gotta go! Blah, blah.
Here's my advice. GO TO THE PARTY! I say this for two reasons. (1) You need to get to know his B-school friends and be part of their social scene or they will always think of you as the party-pooper. (2) Make the effort for him, and know that a day will come when you're supposed to be going to see him and a concert or a friend's b-day party falls on that weekend and you will want to stay put. Then you have the right to turn the tables.
But seriously, yes the party will be dumb. GO. Just go. You need to be a part of his b-school life - you don't want to be left behind. So go and have a wild time and make sure all his new friends know how fantastic and fun you are. After that, they'll be telling hiim that he can't go to the parties if he doesn't bring you.