the main error in the movie plot still remained.
There was no logical reason for Superman to leave earth for five years. Especially since he didn't discuss it with Lois before hand.
Obviously he'd slept with the woman, so they had a strong relationship going, yet he just left without a word.
Unforgivable and unbelievable.
Mr. Beeto has written a wonderful fanfic,
"Family Reunion" , which gives a plausible reason for this and also clears up several other untied plot threads.
He gives a very plausible reason for Superman running out on Lois without saying a word to her.
I highly recommend this fanfic.