I invited three friends (we met at uni, we're now mid 20s) out for dinner to celebrate my birthday this weekend. Three of us are currently single, the other has had a partner for about 6-12 months. The four of us agreed a time and a place a few days ago. However this afternoon the coupled friend has messaged me to ask if it's ok if she brings her boyfriend too.
AIBU not to want him to come? I don't have any issues with him personally, but I've only met him once and while he seemed nice, it would totally change the dynamic of my birthday dinner. But I don't know how I can say no to my friend without making things awkward.