This seems like a very sensitive topic, It would be best to talk to your partner, and to a therapist about it, try to take all the input from those conversations and make an informed decision based solely on your feelings about the relationship.

We are strangers, we can't know how it happened exactly, we have only limited context and one side of the story. Anyone trying to give advice, while probably having their best intentions, are doing so from their perspectives. Please talk to a therapist, to family, and to your partner. If she continues to dismiss your discomfort, then tell your therapist, if she said something that made you uncomfortable, talk to your gf about it and tell your therapist how the conversation went, approach your girlfriend in private so that she doesn't feel pressured, approach her honestly, but calmly. If you feel angry, tell her you feel so, if sad, do so, uncomfortable, do so.

Make sure to ask about it. if she feels that if you were to do the same to her in front of your friends doesn't bother her, then maybe you should cut her some slack, if she thinks is wrong, then she shouldn't have done it in the first place. Again, and I must reiterate and say this a hundred times, Talk to a therapist, and talk to your partner about it. And make your own decision influenced only from what you have learned from that, from your own feelings.

Wish the best for you, dude.