If you get cold sores, does it always mean that you have herpes?

My gf has been getting cold sores forever, so i was told, but, does it always mean someone has the herpes virus?
Update: so, it could just "develop" and she might not have herpes?
Update 2: alot of these links say people should stay away from the infected person...the problem is, i don't want to stay away
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