When Tamar brought the bread to Amnon he took hold of her, and asked her to come lie with him to have sex. Tamar said, "Please don't do this, do not force me, because this should not be done in Israel, don't do this foolishness. Tamar said that it would be shame for her, and Amnon would be like one of the fools in Israel.
Tamar begged Amnon to simply go to the king, David, their father, and ask for her hand in marriage, and Tamar told Ammon that David would give Tamar to Amnon if he would so much as ask. Amnon would not listen to Tamar beg him to ask for her hand in marriage, but instead he was stronger than she was, so he raped her there.
Now what I don't understand is that moments before he loved her, then after raping her, he hated her. The Bible tells us that his hatred to her was greater than the love that he had for her earlier. So then Amnon told Tamar to get out. Tamar told Amnon you don't need to make me get out, because making me leave is a greater evil than raping me. But again Amnon would not listen. Amnon had his servant force Tamar out, and have the door bolted. Tamar was wearing a colorful dress that all the virgins who were daughters of the king wore. She put ashes on her head, tore her dress, and went with her hand on her head and crying.
Absalom plotted to kill Amnon because of this for two years. Then Absalom talked to David about having all the kings sons come with him to shear sheep. David argued with Absalom, and then Absalom asked David about having Amnon come with him to the sheep shearing, and David gave in and allowed all of them to go. Absalom told his servants to observe when Amon was drunk and then kill him, which they did. All the kings sons got on their mules and escaped, only Amnon was dead. Rumor came to David that Absalom had killed all his sons, but he soon learned that Amnon was the only one dead. David mourned for his son Amnon, and Absalom fled and was gone for three years. Eventually Absalom took the hearts of the people and led a revolt against David. Eventually Joab killed Absalom, and David mourned for him. Adultery was costly for David.