you only live once

usually if many girls are in love with same guy, they think it's taboo to have sex with the same guy 

if many girls are in love with the same guy, 

then many girls could have sex with the same guy 

and later when girls become older they could get their own boyfriends 

or if many girls are in love with the same guy, they could forget about him and get their own boyfriends 

and later when those girls become older they could switch to new boyfriends