John Gill Commentary 2 Samuel 13:20

"And Absalom her brother said unto her, Hath Amnon thy brother been with thee? but now hold thy peace, my sister: he is thy brother; take not this thing to heart. So Tamar remained desolate in her brother Absalom`s house." — 2 Samuel 13:20 (ASV)

And Absalom her brother said to her
Either meeting her in the street, or rather when come to his house:

has Amnon your brother been with you ?
been rude with you, and lain with you, which is the meaning of this modest expression; which he guessed at, having heard of her being sent to his house, and knowing his lustful disposition, and seeing her in such a forlorn condition: he calls him Aminon, for so it is in the Hebrew text, and not Amnon, by way of contempt, as Kimchi observes:

but hold now your peace, my sister ;
be silent, take no notice of this matter, say nothing of it to the king, nor any other, keep it in your own breast, and make yourself easy:

he [is] your brother, regard not this thing ;
it is your brother that has done it, and not so disgraceful as a meaner person, done in the heat of lust, and a youthful one, and should be forgiven; besides, to divulge it would bring disgrace upon the whole family, and no recompense would be obtained by telling the king of it, since he was his son, his firstborn, and heir to the crown; this he said not out of love of Amnon, but as desirous of gratifying private revenge upon him for it when opportunity should serve.

So Tamar remained desolate in her brother Absalom's house ;
not seeing any company, being filled with grief and shame, and none applying to her as a suitor, knowing she was vitiated; how long she continued here, or lived after this, is not certain; no mention is made of her afterwards.