Treated differently than my bf brother gf because they know her longer than me

I’m dating with my bf since 2 years and I’ve met his family 1year ago. We are both 25
He has a brother who is dating a girl since 3years and he introduced her the same year they got together. He’s 27 ans she’s 26.
I noticed that several time, my brother and his family or his sibling would do things (little parties, movies nights etc…) where she’d be there and I would not be invited
I told him about that and how I felt excluded
He told me that because his family know her for 3 years now so she’s family now
He added that I’m also family for him but he doesn’t know for his family so that’s different
That’s kinda hurt me like maybe that’s true she’s now considered as family for everyone like in one hand they had more time to know her it’s true but idk he didn’t have to tell me that.
And he got me feeling like I had a different statut from her

So it’s like now I have to be expected to be treated differently from her because they know her longer than me, it is normal ?

Like I also have brothers and sisters, if they’d introduce me to their partners I’d not treat each differently according to the time I know them

The person I’m more mad at actually is not my bf’s family but my bf bc I think it’s his role to think about inviting me to those stuffs since I’m his gf
But he will not bc of this excuse…