does this bother anyone else?

so my boyfriend of a year and a half always adds random pretty girls on Facebook that he doesn't know but usually live around us somewhere. I've told him it bothers me bc I get jealous and insecure, like he is looking for someone better and prettier. he says I'm making a big deal out of nothing. But yet he won't say why he adds them or why he needs random girls on his face book. am I wrong to be upset or should he respect my feelings and quit?