I’ve not read any studies looking specifically at PrEp to prevent the transmission of HSV 2 and I think until that study is done, I wouldn’t recommend it.
The study of Tenofovir gel is sturdier and seem to me to be a reasonable option, except I’m not aware of the ability of anyone to prescribe this for this purpose at this time. it certainly is not yet FDA approved for this purpose. Are you aware of someone who would prescribe this for her and is she willing to use something that is not FDA approved for this purpose?
I think the taking of antiviral meds by the negative partner is unsupported, correct. I would say that if you have sex with this parter and right afterwards, she recognizes an outbreak that she has not previously recognized, a high dose of antiviral medication MIGHT be helpful, if taken immediately, to reduce the risk of the virus establishing latency.
These are just my opinions – you might find an ID doc who feels differently.
Terri