Ladies??? 10,000 bucks for the winner.?

Answer me these few questions: So, I went to my girl's school today and one of her loud friends was talking about how my fiance tripped some asain dude, and every one started laughing at her. Is that the same as flirting? I dont know if i should marry this chick if she is gonna be flirting behind my back, it pisses me off cause sheis such a good girl to me, but I wont put up with her flirting with another guy. What are your thoughts?