Hi Shelley,
I don't mean to bust in on your forum like this, but I thought, if you didn't mind, I'd like to give my $.02
Anyhoo, It sound to me like your guy has a little bit of social anxiety. He's probably nervous all the time meeting new people, but now that he's in line to meet family members he's probably a little more apprhensive. I'm sure he wants to make a great impression on your family, but it may be feeling a little anxious that he won't. Maybe you could talk to him about it. Let him know you understand his feelings, but you would really appreciate it if he was at the party.
I think it's only fair that he go, afterall you did have to meet his ex-girlfriend.
I hope everything works out.
PPL,
Emily