What does Sir Percy do when Marguerite asks if he can love her again?

In essence, Percy tells her it's too late.

‘It is perhaps a little difficult, Madame,’ said Sir Percy, after a moment of silence between them, ‘to go back over the past. I have confessed to you that my memory is short, but the thought certainly lingered in my mind that, at the time of the Marquis’ death, I entreated you for an explanation of those same noisome popular rumours. If that same memory does not, even now, play me a trick, I fancy that you refused me ALL explanation then, and demanded of my love a humiliating allegiance it was not prepared to give.’