1. I doubt that her swab test was flawed though I have seen it happen, yes. I follow up antibody test wouldn’t be a bad idea.
2. It is possible that you have HSV 1 both orally and genitally, yes. But the odds of you transmitting it to her if she already had an oral infection are very slim indeed. She could certainly have had HSV 1 genitally prior to this encounter. She could have acquired HSV 1 orally and genitally at the same time prior to this encounter. I have only seen one case in 32 years of someone acquiring a new HSV 1 infection genitally after a confirmed oral swab. When you say cold sore, you mean on the outside of the mouth, right, not a canker sore on the inside of the mouth?
3. I don’t have an answer for that, honestly. But we certainly see it happen = people are infected for years and then start breaking out with no known trigger.
If you want to get back together, the herpes should not be an issue at all in that situation.
Terri