So I was at a pretty big pregame for a music festival with my girlfriend.

We've had a very RP relationship, she is super invested in me and never goes out without me etc. It's very red pill. Very captain first mate dynamic.

At this pregame I went around talking to everyone, having a good time and all, talking to plenty of girls and flirting.

So I go inside and see my girlfriend sitting on the couch with a guy, and he has his arm around her and she is leaning into him. She looks at me then looks back.

I shrug and continue with having fun, I don't pay attention to it or care.

Then later when we were alone walking to the festival I looked at her and said "I saw you in there with that guy. There's no other reason that you would do that other than to make me jealous. If you do it again I'm ending our relationship."

And then she said sorry, I changed the subject and pretended like it didn't happen. Then I unintentionally got lost from her the entire music festival. So an unintentional soft next?

This is also super out of character for her. I've never had her do anything like this before, whenever we go to parties she doesn't even talk to guys that aren't friends with me.

Did I handle this correctly?