Thanks to its multiple infection sites, herpes has the unusual property that two people, neither of whom have an STI, can have sex that leads to one of them having an STI. It's a spontaneous creation of stigma! And if you have an asymptomatic infection (very common), there's no way to know whether it's oral (non-stigmatized, not an STI) or genital (stigmatized, STI) since the major strains are only moderately selective.