Worried about my girlfriend going to carnival

Lookimg for some advice. My girlfriend and I have been together over 2 years now and our relationship is amazing in and put of the bedroom we even like to have fun with other people in the bedroom if you know what I mean. My girlfriend has been going to the Nottinghill Carnival for about 8 years now but not been since she met me. She hasn't been for a few different reason one year her friend who she goes with couldnt go, one year she couldnt afford it as she likes to wear the costume dance and be a part of it all, ive not asked her not to go but I know she wants to go next year and for some reason I have major issues with her wearing the skimpy costumes and dancing how they dance with other guys. It confuses me so much as we like to play with other people in the bedroom, I lole to watch her with another guy but I can't bear to think of her dancing with other guys at the carnival. Can anyone help me understand why I feel like this?