H.H.
When my now 37 year old sister was 14, she dated an 18 year old. Only after learning they were sleeping together did my parents forbid it. They snuck around for about 2 years after that. forbiden love! Through observing what other parents have done, and all the rules I watched my own sisters and friends break, this is what I decided will work best when my kids are old enough to date: all dating under the age of 18 should be only as part of family events. No going out on alone dates, and no cars. But they can spend time together at family-get-togethers and in the home when parent's are home.
I knew one family that did it this way and it worked so well for them. Since the only time they were allowed to spend together was focused on family events, it drove away the one's that were only interested in sex. Since the newcomer was forced to get to know the whole family, they were less like to treat eachother as sex objects and were more respectful of the rules in general. This method demonstrated to children that forming a friendship happens before the getting naked part. this really eliminates the forbiden love element.