Competition Quotes in The Other Boleyn Girl

How we cite our quotes: (Chapter.Paragraph)

Quote #10

There was too much to send in one message. There were long years of rivalry and then a forced unity and always and ever, underpinning our love for each other, our sense that the other must be bested. (49.131)

Mary acknowledges that she and Anne were rivals first and sisters second. But to her, the complexity of their relationship strengthened their bond with each other. Do you think she's right? How does this play out throughout the novel?