I see two sad smileys in your original post and only read about some underlying "obligation" and no enthusiasm as in:
Yeah, we are going to BBQ and my neighbors can grill a mean rib eye and they are wonderful people with whom I have deep, fascinating conversations.
Obviously you don't feel like going deep inside so don't go
No thank you is a complete sentence you know. You don't
owe them the pleasure of your presence which actually might end up quite unpleasant if you are craving a drink and being a sour puss or even worst pick up a drink and end up making a jackass of yourself.