At dinner, what does Daisy accuse Tom of doing to her?

The very first chapter of The Great Gatsby (Fitzgerald) features Tom Buchanan as a brute. Nick has already described him as a nationally prominent football player in college and upon meeting him again now, says he has a "cruel body" (11). At the dinner, Daisy examines her little finger, which has a "black and blue" knuckle. She blames Tom for this, although she says he didn't mean to hurt her.  And then she says he is "a brute of a man, a great big hulking physical specimen..." (16). We never do see Tom hurt her deliberately, but later on in the novel, Tom hits his mistress, Myrtle Wilson, because she continues to want to say Daisy's name, and the more we learn about Tom, the more likely it seems that he has hurt Daisy other times, too. There are seldom any references to Tom in which he is not portrayed as somehow brutal.