And he pined for her exceedingly, so much so that, out of love for her, he became ill. For, since she was a virgin, it seemed a difficulty to him that he would do anything dishonest with her
Other versions
King James Version
And Amnon was so vexed, that he fell sick for his sister Tamar; for she was a virgin; and Amnon thought it hard for him to do any thing to her. English Standard Version
And Amnon was so tormented that he made himself ill because of his sister Tamar, for she was a virgin, and it seemed impossible to Amnon to do anything to her.New International Version
Amnon became frustrated to the point of illness on account of his sister Tamar, for she was a virgin, and it seemed impossible for him to do anything to her.