Jamieson, Fausset and Brown on 2 Samuel 13:12-14

12-14. do not force me--The remonstrances and arguments of Tamar were so affecting and so strong, that had not Amnon been violently goaded on by the lustful passion of which he had become the slave, they must have prevailed with him to desist from his infamous purpose. In bidding him, however, "speak to the king, for he will not withhold me from thee," it is probable that she urged this as her last resource, saying anything she thought would please him, in order to escape for the present out of his hands.