I (19M) am planning a trip with my friend group. It’s me, two of my guy friends (21M and 19M), my two girl best friends (both 19F), and my girl best friend’s cousin (19F). The cousin isn’t part of the friend group but is really close with my best friend, so she invited her. One of the guy friends (21M) also isn’t someone I regularly hang out with, but we’re cool and he’s the boyfriend of one my girl friends, so he’s coming too.

My girlfriend (18F) is upset because I didn’t invite her. She said she wouldn’t have minded not being invited if it was just the regular group, but now that two people outside of it are going, she feels hurt that I didn’t think to include her too. Her issue isn’t that there are girls going—it’s that people outside of the core group are coming, and she feels like that makes it fair game.

I didn’t invite her because this trip was planned with the friend group in mind, and I didn’t want to change the dynamic. The cousin is only going because she’s staying with my best friend, and the older guy friend is more of a “friend of a friend” situation. I didn’t think of it as a big deal.

Now my girlfriend feels left out, and things have been a little tense. I wasn’t trying to be shady—I just genuinely saw this as a friend trip, not a couple’s trip.

AITA for not inviting her?