AITA for fighting my bf about him not introducing me to his big friend group?

I’ve (F24) known my bf (M26) for almost 3 years. I’ve met his family and his “boys” which is his 4 closest/best friends. He has a big friend group from college that includes those 4 closest/best friends and I’ve never met the other 10+ people (the group is mixed with boys/girls). It never really bothered me until they invited him to go celebrate NYE. I asked if I can come? And he said he’s not ready to introduce me to them yet. That’s all he can say to me - “I’m not ready.” When I ask why, he says the same thing.

My friends and I have brainstormed a few reasons. But none of them really makes any sense. He’s told me that no, he never dated nor hook up with his friends and don’t want me to meet them, or his friend group is judgy or just assholes but why would he be friends with these people if they are? I just can’t imagine him like that.

We had a huge fight about this and I am even considering this as a dealbreaker. AITA?