But that's probably more about the people behind those ideas and the morals they have rather than the act of sex itself :P Like as one example, I wouldn't be surprised if many of the people who don't believe in sex before marriage also don't believe in divorce, regardless of how good their relationship still is. Like I said, causality is up for grabs. But I do think there's something to the theory that a relationship is stronger if it first succeeds non-sexually. A relationship built around sex is not really a relationship. No matter how good it is in the beginning, it WILL get boring eventually and then all that will remain is two people who, likely, cannot stand to be in the same room as each other. Sex is an important part of a serious relationship, but it's not everything, not by a long shot. A good relationship has to be built around friendship, around sharing common interests and genuinely enjoying each other's company, or it is doomed to fail.