Why do American guys think I will steal there girl when I they no I wont?

Idk at my american high school everytime i pass a girl and the girl is with her BF they think like im gonna steal her or like make her break up with him to have me or idk somthing like that its real annoying i've never had this GF in Russia we dont use the word girl freind or boy firend etcratra. and my nick name in my school is russian spy or commie kid. idk just asking is all and dont rat on me because i put this up i was just board...