This is a great question to consider, because, to a large extent, Bendrix is a character that remains very low in self-awareness throughout the novel, as his relationship with Sarah shows. During the course of the novel, Sarah and Bendrix diverge through the different choices that they make concerning love. Sarah chooses divine love and dies, whereas Bendrix chooses romantic love and, having lost Sarah, then begins to hate her. Divine love is shown to be selfless and romantic love is shown to be open to selfishness which can so swiftly be tainted by hate. The love that Bendrix has for Sarah is very confused by selfishness, as is shown when Bendrix rejects Sarah's wishes to be buried and insists that she is cremated. He, unlike Sarah, shows that throughout the novel his love is conditional and based on his own selfish needs and desires. If there is one way that he does change, it is in the way that by the end of the novel he concedes that God is not an opponent that he can triumph against. Consier the last "prayer" that ends the novel:
O God, You've done enough. You've robbed me of enough, I'm too tired and old to learn to love, leave me alone for ever.
What we can say that Bendrix has learned is that God is not so easily beaten as Bendrix thought He was in the battle for Sarah's affections, and that Bendrix has learnt something about his inner frailty and weakness as a human.