Simple thought here.....
Go if you feel like going, don't go if it makes you feel uncomfortable.
I don't want to go to any functions if I don't know at least one person and I have to know that person enough to hold a conversation(s) through out the whole ordeal. Logic sinks in after a few minutes when no one comes up to you and you are holding a drink in the corner some where.
THOUGHTS come rushing in: "What am I doing here? I hardly know anyone, and yet I came. When is this over?"
Overall, don't go if you and him are not close, it would just be uncomfortable especially wedding invites since they are personal.