It seems odd that a) Miss Teschmacher would still help Lex after he tried to kill her mother and b) Lex would still keep her around after she foiled his plan. But, there's a fairly obvious romantic undertone to their interactions. That's plain. What's less plain is what I only picked up from The Donner Cut. There's a line in which Lexi implies he'll knock out her teeth for what he perceived as an insult. With this in mind, we can look back at some dialogue from the first movie, especially when he straight-up calls her an idiot on the level of Otis or pimps her out to further his plan. My conclusion: theirs was an abusive relationship, to which people are known to return despite every logical reason being against it.
The bully at the diner ends up with a completely shattered hand after tormenting and attacking Kal-El. Sound familiar?
Not to mention Clark let the man hurt himself (pulverizing every bone in his hand from punching what was pretty much a block of steel) instead of outright attacking the guy.
Superman voluntarily gave up his powers to experience "life as a mortal", a process from which "there is no return", according to Lara. However, he recovered his powers once he realized the stakes involved (Kryptonian villains took over the Earth, with a little help from his archenemy) and forgot about what he wanted (to be with Lois). Seems like Jor-el and Lara set this up as a Secret Test of Character, didn't they?
From the theatrical cut: As a depowered Clark comes out of the chamber, a lingering image of a costumed Kal-El remains. Similar to what happened in Superman III, this time Superman split into mortal (selfish, weak, yet tangible) and heroic/immortal (who vanishes in the chamber, at least until later). To re-power, either he could have merged back or the "good" side may have prevailed (like in "III", minus a fight).
When at Niagra Falls, Lois mentions to Clark that he's "blind" because the spray of the Falls has covered his glasses. As he awkwardly tries to clean them, she slips them off him and does it for him. Why didn't Clark notice that they were covered with gunk? Simple; he has x-ray vision and didn't realize anything was on them in the first place. He didn't notice until Lois pointed it out to him and he focused on the glasses directly.
In the Donner Cut Superman destroys his Fortress of Solitude... with Lex Luthor apparently still inside it! Granted Luthor was a jerk at best and a Psychopathic Manchild at worst but still... harsh. Of course, the Arctic Police had probably carried off the villains by that point.
What if Zod had won? Then Superman would have become his third henchman, and there was quite literally nobody in the world who could have stopped them from tyrannical rule. It would be misery for the Earthlings until Zod got so bored he'd just kill everybody.
