Sadly the answer to that is No there will always be a risk of you transmitting the virus to your partners genitals even in the absence of an outbreak as the virus sheds several times a year and no one really knows when this takes place ..... however if your g/f already has HSV1 orally it will significantly reduce the risk of her contracting it genitally generally if someone gets oral cold sores the likelihood of the virus changing site is very low ....
It might be an idea for her to get tested she may indeed have HSV1 and have never had a cold sore to date, anything is possible as Herpes is such a variable condition and not every person experiences outbreaks or identical symptoms but are still infected therefore they don't know they have it .....