Is it okay for my gf to go to ball with another guy? 16M 16F

I Know its not too deep bc were still young and we arent married etc but it makes me uncomfortable that she would be slow dancing and taking photos and stuff with another guy. (I might not be able to go bc i cant afford it and the tickets are $250 plus a suit and other things, I work for all my money and i dont earn a lot vs her who has extremly wealthy parents) also I dont really even feel like going anymore bc thats supposed to be a special more intimate moment and i feel easily replacable i dont know if thats a maturity thing tho