What is the main conflict in River God by Wilbur Smith?

At its heart, Wilbur Smith's novel, River God, is a love story. The narrator, Taita, is a slave. He is well educated and loyal to his mistress, whose name is Lostris. Lostris is a young lady at the beginning of the novel. She is full of romantic ideas and interested in her childhood friend, Tanus, as a future mate. Tanus is a kind young man, fiercely loyal and equally interested in Lostris. The two make promises to one another, but fate intervenes. Lostris is the only daughter of a wealthy noble, Lord Intef, who ensures his favor with the Pharaoh by promising his daughter in marriage. Pharaoh Mamose believed that a young and virgin bride would provide him with a well-bred heir to his crumbling kingdom. Lostris went reluctantly to Pharaoh's palace and brought Taita with her.