It seems, however, that Cohen's argument stipulates we have no ability whatsoever to resist relationships outside of our partnerships. That being the case, one assumes we should thus indulge ourselves as we desire, but only if we use a condom ... to slow the spread of HIV, of course.
Anyone who argues that HIV's spread can be checked by the use of condoms (especially with their failure rate) is living in a dream world. And they're certainly not cheaper than abstinence. That's not to say that abstinence and staying faithful in a monogomous relationship will wipe it out either. You can only do your part to protect yourself.
People CAN abstain from sex outside of committed relationships. It's not impossible, and though it is hard, it helps if others can recognize that it is right to do so. The Catholic Church helps here in ways that Mr. Cohen will never understand.