I wonder what finding out a you have an STD feels like. The sex was good, and you're feeling great. A few days later, you have a burning sensation in the shaft of your penis, and for a split second, think "fuck!" but disregard it. Couple more days pass, and it's definitely worse than before. You start getting paranoid and worried about going to get it checked. You get checked, and it's venereal. That based feeling about girl you just fucked turns into hatred. You bring it up, and she denies it was her, says you got it from someone else, when you fucking KNOW it was her.
Must be awful.