And who's going to just take the word of a potential sexual partner who merely says that they're "undetectable?" That's stupid on steroids.
Undetectable is a play on words...The most recent tests ability to detect virus is down to about 20 copies per cc of blood. So “undetectable” means less than 20 copies per cc. Hiv is still present. The WHO or UNAIDS act as if “undetectable” means untransmissable.(Not absolutely true)....plus the viral genome integrates itself into host dna....so hiv is always present...those infected...especially if a new mutant arises or the infected misses a few doses can be infectious again.
HIV is exposing the inability of too many humans to control an infectious agent. Both in thought and deed.