I like the premise, Ann. Most of us share the idea that Clark shouldn't love anyone but Lois, much less marry anyone else. So the question is, how he would end up married to anyone but Lois in the first place?
In my opinion, he could be tricked into a marriage. Let's say that he's dating Lana Lang in his late teens. He might stumble across kryptonite, accidentally gets drunk and hungover. Lana tells him that they made love, which of course isn't true, and she got pregnant.
Later on, he might find out that she fooled him into marrying her, but he cannot prove it. For the good of the child, he stays with Lana. There's bound to be a strained relationship between the two of them, getting even worse as Clark meets Lois.
