In addition, a single exposure to an infected sex partner usually does not result in infection (the transmission rates for different STDs differ between them but for female to male transmission, none of the rates exceed about 20% per
episode of intercourse (that’s the rate for gonorrhea) and for some, like
HIV, the risk is far smaller, like 0.01% per sex act). Thus you can take some comfort there.
Add to that multiple negative tests for HIV with reliable tests.