But its not just a small mistake, its a colossal mistake, one only an emotionally immature person could make. So, I guess he is not emotionally mature/strong enough to say goodbye yet he sure has no trouble sleeping with her.

How dense does one have be to be to not realize the great amount of pain you would cause a loved one by suddenly disappearing for over 4 years without even saying a word. He had to have known it would have caused an extreme amount of pain for Lois. But yet, he does not say anything to her because it was too difficult for him?! I'm sorry but this is so lame and so out of character for Superman. The writers wanted to create drama for Superman, one in which he could not physically fight back, but in doing so they totally compromised his character.