What is the main conflict in The Virgin's Lover by Philippa Gregory?

At the time of the start of the book we see Amy Dudley (previously Amy Robsart) trying to convince her disgraced husband Robert Dudley, to accept his defeat and to build a quiet life in the country with her rather than try to attain place and favor at court. Robert Dudley's whole family was disgraced when his parents tried to rebel against Queen Mary (now known as Bloody Mary), and was trying to earn a name for himself in battle and in charm by attending the courts. As a passionate Protestant, he awaiting the day that Queen Mary would die and the natural successor would be Queen Elizabeth, one of Henry's children.