He didn't have control. Ammon fell in lust not love with Tamar and notice what happened when he got what he wanted v15. One reason is to build self-control. If my wife knows that I was able to control myself and my sex life before marriage then it builds trust in her mind and strenthens our relationship when I'm travelling. But if this person is prepared to indulge in sex outside of marriage then how do we know that they won't in the future when they are married.
Moral purity has the opposite and strenthening effect on the relationship.
Here is a man who is self-controlled, prepared to hold back on immediate pleasure out of love for his future partner and love for the Lord. So restraint and self-discipline before marriage form the foundation of loyalty, stability and permanent unity within marriage. A better word would be fore-play, because that's exactly what it is. It is to arrouse your partner in preparation for sexual intercourse. The more they pet the less they talk.