He wanted nothing less of Daisy than that she should go to Tom and say: ‘I never loved you.’ After she had obliterated four years with that sentence they could decide upon the more practical measures to be taken. One of them was that, after she was free, they were to go back to Louisville and be married from her house – just as if it were five years ago.

F. Scott Fitzgerald

The Great Gatsby, Chapter 6. Gatsby wants Daisy to not just end her relationship with Tom, but to tell him she never loved him. Gatsby doesn’t want others to have Daisy’s love, he wants her completely for himself.