AITAH for not letting my friend’s new girlfriend come on our annual trip?

Every year, my friends and I (all in our early 30s) go on a weekend trip together. It’s a tradition we’ve had since college, and it’s always been just our core friend group—no plus-ones, no significant others. Not because we don’t like them, but because this trip is our time to catch up, reminisce, and just have fun like we used to.

This year, my friend “Mike” (32M) started dating “Jessica” (28F) a few months ago. None of us have really gotten to know her yet, but from what I hear, she’s nice. A few weeks before the trip, Mike asked if she could come along. I reminded him that we’ve always kept this trip just for our group, and that it wouldn’t be fair to change the tradition now.

Mike got frustrated and said that since they’re getting serious, she should be included. I told him she’s welcome to come on other trips, just not this one. He ended up backing out of the trip completely, saying he didn’t want to go without her. Now a couple of our friends are saying I was too rigid and should’ve just let her come.

I don’t think I was wrong for wanting to keep our tradition, but now I’m second-guessing. AITAH?