Herpes, as you probably known, is a virus .The virus caused a sexually transmitted infection that is characterized by outbreaks of painful blisters on the genitals or inside the vagina. When the blisters are present, the risk of spreading the virus to someone else if you have unprotected sex is very high, as these blisters contain very high levels of virus.
When the blisters die down the virus does not go away completely, it just remains dormant for a while. From time to time it will reactivate and cause new blisters (with high risk of spreading). When the virus is dormant, the risk of spreading the virus is less. However there is still a risk, in part because there is probably still some virus in the vaginal secretions and also because you may have a small outbreak and never notice.
Unfortunately, the only sure way to decrease spreading the virus is to always have protected sex with a condom. Medications can also help, because they can suppress the virus some and decrease the number of outbreaks / reactivations. However, there will still be some virus present, so taking medications is not a 100% fool proof solution.
Talk to your primary care or OB GYN doctor
about this problem for more advice.