I heard a great analogy on Catholic Answer Live the other day. A caller asked why we opposed "comprehensive" sex education programs, that teach abstinence first, but also stress condoms to prevent disease and teen pregnancy just in case some kids are unable to abstain. Fr. John explained that it was like a teacher telling a student that cheating on exams was not allowed. Just flat wrong, don't ever do it. But, if you are going to cheat, here is a website with all the answers, and be very discreet when you text your friends during class, so that you will at least get a good grade and not have any consequences from your cheating.
Don't cheat, but if you do, here's how you should do it. But don't. We really mean it. Wink, wink.
Don't have extramarital sex. But if you do, at least protect yourself from consequences.
It's the whole idea of consequences that used to keep people from sinning. The more modern society tries to spare us the consequences of sin (and excessive debt), the more people will continue to pursue pleasure first and expect a "bail-out" when the logical and natural and inevitable consequences of their actions catch up with them.