Answer:
During the encounter between Tom and Gatsby at the Plaza hotel, Daisy crumbles rapidly, backpedaling on her assertions of loving Gatsby and never having loved Tom. She says to Gatsby
"Oh, you want too much! I can't say I never loved Tom. It wouldn't be true"
Tom quickly capitalized on Daisy's wavering loyalties to reassert his control over her. He tells Gatsby that "there's things between me and Daisy that you'll never know, things neither of us will ever forget." He also goes aggressively after Gatsby's shady past and the insecure foundation his wealth is built on, knowing full well how much money matters to his wife. Daisy most likely realizes that she is a fantasy figure to Gatsby, a representative of his desire for lost youth, wealth, and security and that his needs are insatiable and unrealistic. Her relationship with Tom may be troubled, but, as he reminds her, it's real and rooted in a shared past.