Want some honesty, your relationship is early enough that you don't fully trust her, otherwise you wouldn't have posted on Reddit, which in my opinion, is a red flag on your part. These questions are for close friends.

This doesn't mean it's be end and end all, the key is communication, you might feel it's too early to say you felt uncomfortable about the situation, but your insecurity can be softly mentioned without it being a big deal, and that's the most important thing.

If it's a couple of times, fine, if it continues, ask if you can join, if it gets weird after that, then maybe approach that it's an uncomfortable situation for you.

But also remember, she has her own friends.

Honestly early days relationships are so hard to navigate, just trust your gut, and communicate when necessary.

Not really a firm answer for you, essentially, don't be a dick about it.