It's her own protection, else if have too many bf doing her, she
will get bacterial vaginosis and it's going to smell like a fish
forever. 
Spare a thought for her too. I am sure you don't want her
to have ccb right.
Certain factors have been identified that increase the chances
of developing bacterial vaginosis. These include multiple
or new sexual partners, vaginal douching, and cigarette smoking. However, the
role of sexual activity in the development of the condition is not
fully understood, and bacterial vaginosis can still develop in
women who have not had sexual intercourse.
http://www.medicinenet.com/bacterial_vaginosis/article.htm