Thanks for the comment...It has been a long and burdensome week since finding out about it. We are both remaining positive.
BV is not and std per se. It can be caused by sex but not transferred sexually. I got it when my ex-husband cheated on me and then had sex with me without showering in between. Every woman's vaginal flora (balance of yeast and bacteria) is different. When the other woman's vaginal secretions mixed with mine, then it upset my balance and caused the bv.
To further prove that. I have also gotten bv after a threesome. Again, mixing of vaginal secretions.
Another common way for a woman to get bv is anal to vaginal sex. The bacteria from the rectum does not belong in the vagina and definitely upsets the vaginal flora. This is the same if after using the bathroom she wipes back to front. A woman should always wipe front to back to avoid infections of this type (and UTI's) as well.
So, if you don't have anal sex then vaginal, she is safe. Most of it is prevented with correct sexual hygiene.
Don't worry. It is more a nuisance like a yeast infection. Women get bacterial vaginosis quite often without having sex.