Why does the party sometimes look away when party members visit Prole prostitutes?

The Party feels that the sex-instinct in the male is difficult if not impossible to break. At times they will "look the other way" if an outer party member has sex with a Prole prostitute as long as it only involves a sexual act. The Proles do not concern the Inner Party. They see the encounter as a release and less reason for a party member to hold thoughts against the Party.