When you have made the most precious and intimate bonding gesture it is possible to make to another human being, then what is left for you when you really mean it ?
Im with whiffey on this, Im not saying that you have to be married, but if you mean that two people meet find each other attractive and have sex, I wouldnt, thats how diseases are spread and what have you then got to give to the Woman or Man that you love, just another sh@g!!