If she is just "one girl", you shouldn't be together with her even if she didn't have cold sores. Catch my drift? Chances are you already have herpes anyway.
>>but most people (about 75%) doesn't have simptoms at all
Personally I'd have no problems with cold sores 3-6 weeks a year for someone I love. Small price to pay, you will have to make greater sacrefices than that to get a relationship to work.