Here’s something to keep in hand when you tell your girlfriend you’ve been cheating on her. “Honey, I was only doing it to make the partner pool cleaner.” Jokes aside, the theory makes sense. If a sexually reserved individual decides to have sex with someone new, he thereby lessens the chance that that individual will have sex with someone less prudent, and likely become infected. If that same reserved individual has sex with someone new and becomes infected, the infection will more likely end with him, and not be passed on to someone more promiscuous.