Many young couples don’t understand that sex is a progressive activity that culminates in intercourse. They think they can just start downhill and then slam on the brakes when they reach the bring of intercourse. However, this is a misunderstanding of how we were created. Once arousal begins it is unnatural to stop short of full expression.
Sexual stimulation was designed by God to prepare marriage partners for intercourse, not as a pleasant activity that can be easily interrupted. Stimulation, or foreplay, is intended for one thing only: precipitating a married couple into a complete expression of their sexuality.
Not only is the interruption of sexual foreplay almost impossible, but it is also highly frustrating. When sexually frustrated, our bodies don’t care about Christian convictions. …
Lust has an insatiable appetite. The more we feed it the hungrier it gets. With each progressive step of sexual intimacy we take, desire is increased, never decreased. That’s why allowing ourselves “minor” compromises of ever increasing sexual intimacy ultimately violates the spirit of the law and leads us to commit sexual sin.
One of the worst preparations for marriage is to become passionate before it takes place. Many women today complain that their husbands don’t know how to express intimacy and affection outside the bedroom.
Josh McDowell and Dick Day, "Why Wait?" p.400