Shouldn’t be able to reinfect each other. right ?

I’m symptomatic and she’s asymptomatic. 

If you are both confirmed as having HSV 2, it is very unlikely that you would now infect each other, correct, though not impossible. 

And you can certainly go through life without ever having an outbreak, but that raises the question for me which is I am assuming that you both know you are infected through maybe a blood antibody test rather than swabs from lesions?  It is important that you look at the antibody test results and be sure the number associated with the positive value is >3.5 or it could be a false positive.  If your girlfriend is asymptomatic, again, check her index value on the blood test and be sure it is an IgG type specific test that was done.  And if she is only having sex with you, she does not need suppression if she is having no symptoms.

Terri

What are causes for a false positive and false negative?

Valtrex would only impact your IgG response if taken right away, when you are first infection, daily.  Is that the case?  If not, then you're OK

False negatives could be due to 1) taking Valtrex daily when first infected or 2) failure of the test to pick up infections.  The IgG misses 8% of HSV 2 compared to the gold standard western blot.  False positives are most often due to someone having a protein in their blood that looks like one of the herpes antibody proteins, but it isn't that.  So about 6% of people who test for HSV 2 with an IgG test fall into the low positive range, 1.1 to 3.5.  Half are false positives.  Of those, 20% will have an indeterminate western blot, which is that same protein showing up on the blot test.  I honestly don't think anyone here needs to take Valtrex for reduction of transmission - only if one of you is bothered by outbreak frequency.  Now if there is some doubt about the diagnosis, that's a whole different story.

Terri

Then my advice about being able to have sex together is void.  You don't know that you have HSV and I think not taking care about transmission would be a bit foolish right now.  You've had no herpes lesions and until you have one to swab OR are off Valtrex for three months and retest with a positive, you don't know that you have herpes.  Taking Valtrex at the beginning of an infection without a lab diagnosis can prevent antibody development so the tests will negative.  If you come off Valtrex and do have herpes, you will likely have an outbreak that could be swab tested and then you might have a clear answer.  I think it's a bit disturbing that a text with a physician when you have no lesions can result in a Valtrex prescription that can alter your testing results without anyone telling you that side effect.

Terri