I guess in the end, Rocco's purity failed him. He's complicit in the murder of Nadia in a supposed act of selflessness for the redemption of Simone, the brute. But how about the feelings of Nadia, did he even consider? Probably maybe but most definitely not and that's the cross he has to bear.
In the end it is Ciro who appeared as the emotional anchor of the family. No wonder he has the film's final words to counter Rocco's "There's no hope now." declaration (even if to self-effacingly proclaim Rocco as a Saint).
The tragic ménage à trois-- bookended by Vincenzo's engagement party and Ciro's surprise rendezvous with his fianceé-- gnawed on their lives 'til all they could have left to hope for is a homecoming to much simpler times.
Will Luca ever set foot on Lucania again?
Will he ever?