Rule number three is no sexual misconduct. How do you define misconduct? That depends on where you live. The social rules are different from country to country and region to region, and what’s considered misconduct in America might be completely appropriate elsewhere in the world. That doesn’t matter; the real problem here is suffering. If something is inappropriate to the society you are in, then it needs to be avoided.
Self-restraint is crucial to a Buddhist. Remember the eightfold path again; right effort, right action and right mindfulness all deal with self-control and restraint.
What does our new friend Thich Nhat Hanh have to say?
Aware of the suffering caused by sexual misconduct, I vow to cultivate responsibility and learn ways to protect the safety and integrity of individuals, couples, families and society. I am determined not to engage in sexual relations without love and a long-term commitment. To preserve the happiness of myself and others, I am determined to respect my commitments and the commitments of others. I will do everything in my power to protect children from sexual abuse and to prevent couples and families from being broken by sexual misconduct.
He seems to enhance the importance of responsibility and commitment beyond simple sexual misdeeds. There is definitely an emphasis on commitment; monogamous relationships and marriage are strongly advocated.