Because girls are not boys, or to put it scientifically, for the human reproductive system to work you need both male and female. If girls weren't girls the human race would die out.
if he flirts with other girls he's probanly just rying to amke you jealous, or just to see how you react!! If he told you "I Love You" and flirts with other girls... he probably doesn't mean it!
You don't.girls, girl's, and girls' are all the same word, girl. They are just different forms of girl. girls is plural. girl's is singular possessive. and girls' is plural possessive. Example: Many...