there is a guy called Mark Gunger, who teaches why it is no bad thing to wait till you find the one you are going to marry. He does teach secular people as well as believers, I guess trying to be salt and light and prevent people fornicating etc. As well as showing scripture makes perfect sense. I highly recommend his teaching if you are wondering this. Not saying this guys doctrine is sound or anything, just his teaching on relationships etc is fine from what I can see... no idea about his other teaching. (He doesn't beat about the bush though so just be aware, some might find his to the point speech and use of humour a bit much.)
It is far easier to ask us all what are the side effects of relationships that don't lead to marriage or don't wait for marriage etc.