What warning does Estella give Pip about loving her?
That she will not be able to love him back. She warns him not to lose his heart to her because she has nothing to give him in return. In her marriage to Bently Drummle, Estella remarks that she brings nothing to the marriage (i.e. no emotional attachment) but that Drummle understands that and doesn't mind. (She is a form of Victorian "arm candy")