You guys simply don`t understand. In this movie, Superman is trying to regain his place in the world as a Superhero and as a human being. At the beggining of this movie, Superman is feeling like an outcast, cause he cant havea relationship with Lois. Moreover, NASA discovers some chunks of Krypton and Superman thinks its his duty to check if theres any survivors. Inside, he wants to find a place where he fits. What place is better than home? So he goes on a trip with the hope to see Keypton alive, or even some survivors `cause inside he doesn`t like that he is the last survivor of his race. So when he gets there, it is a graveyard. Krypton and its history are gone and lives only in storybooks(crystals in the fortress). He comes back more lost. Even worse, he comes back to a world that changed a lot. His mother has a boyfriemd, Kent farm is being sold, Lois articlie about Superman not being needed. He feels insecure and again like an outcast. But now he knows the answer isn`t in the stars. It`s in his heart. So his mom convinces that the world does need people to look upon to. He goes back to Metropolis hoping he would be with lois and see her with a family. Superman always wanted to fit in and he sees the woman he loves happy with another man. He gets jelous cause he cant have that. His planet is gone. He feels alone. But when a disaster is about to happen, Superman is needed once more. Now add Luthor to that, who is trying to destroy the history of krypton for his own personal gain, and destroy what Superman loves.
What i`m trying to say is that this movie is about Superman`s dreams to fit in Earth, to protect and live in it as a human being. So its perfecly resonable that the conflict in the end of the movie is solved and he finds happiness with the woman he loves and son and he`s not alone anymore. If you cant relate to that or u cant understand how great the story is, its not Singer`s fault. Its yours.