Then Amnon hated her with intense hatred. In fact, he hated her more than he had loved her. 2 Samuel 13:15a
No matter what we might think, sin is never satisfying for the long term. Oh, it can bring plenty of momentary pleasure, but when the dust has settled, the end result isn't what we had expected.
Adam and Eve learned this. The fruit was pleasing, but the consequence wasn't worth its taste.
In the story of Amnon and Tamar, Amnon learned this same lesson. He was all-consumed with what he thought was love for his half-sister Tamar. In truth, it was lust. In a plot concocted by Amnon's cousin, the stage was set for Amnon to express his love. What he did was to feed his lust. When Tamar refused his advances, Amnon raped her. Even then, he was not satisfied. Laying with her had not endeared him to her as he had probably convinced himself. Taking what he wanted was far from satisfying.
Eventually, it cost him his very life.
Tamar's full-brother, Absalom, waited two years for an opportune moment to avenge the defilement of his sister. As the story goes, Absalom's men murdered Amnon in cold blood - in the presence of all the king's sons.
Interestingly, there is someone else in this story who probably learned this same hard lesson - the lesson that sin will not bring long term satisfaction.
In an earlier time, David concocted a scheme to satisfy his own lust. The end result of his sin was disastrous. Bathsheba became pregnant. Uriah died. Soon thereafter, the very child conceived through David's lust was taken away from them. Even more devastating was God's promise that the sword would not depart from David's household. Now, this promise was realized. Amnon and Absalom had both learned lethal lessons from their father. Sex and murder didn't solve anything.
Father, there have been so many times that I believed the enemy's lies - that sin can be more satisfying than righteousness. Help me to seek after You. There is nothing on this earth that pleases like You, and the end result is always the same: LIFE - eternal life.