I don't know about this one. If they were just fooling around and not engaging in actual intercourse, that'd be one thing. But ho'ing around can lead to diseases. There's plenty of ways to enjoy being young and widening your sexuality without bringing that level of risk into your and your girlfriend's life.

Not to mention, I'd have to say if you cheat in relationships, you can't say you're an honest person. I'm not saying people who have sex before they are married are immoral, but if you tell somebody 'we're exlcusive' then go behind their back, well, you have limited character in my eye.