He could just have standards or high enough self esteem to know better too!
I rather wish I would have had far more of them years ago. Fortunately I am lucky and have no kids or diseases.
For me I backed off on the sex issue due to simple common sense that it could have far reaching negative impacts on my life just from what mistakes I saw many of my friends having to deal with who where not smart enough to realize the implications of their behaviors like I did.
Watch your a few friends lives go down the drain because of what they did and apply those lessons to your own life and its a real eye opener to want to change. Or at least it was for me.