I think Phil has the story pegged. I'm not going to dig out my old comics to check it, but it does sound like the one he mentions.
In it, a villianous magician (I think it might have been Abra Kadabra) decided to prove his 'greatness' by creating a spell that would eliminate Superman. What it wound up doing was taking away Clark's memory and knowledge that he was Superman.
Freed from the need to protect his 'secret identity' Clark true personality shone through and Lois began to really appreciate this new, more dynamic Clark Kent. They date, and over time, fall in love. They were married and would have lived happily ever after if not for an attempt on Clark's life.
While out swimming in the surf, a bad guy sprays Clark with bullets from a machine gun. Clark was faced away and for some reason was unaware of what had happened. Lois, on the other hand, had witnessed the whole thing from the beach.
Lois rushes up to her husband as he comes out of the surf. She thinks that he must be in shock and at death's door. When she throws her arms around him she discovers that he hasn't been scratched.
Lois realizes that her husband, Clark Kent, is actually the long missing Superman. She sets out to find out what happened and eventually comes across the broken-down magician whose life had come crashing down when no one would believe that he was responsible for Superman's exit. The ridicule destroyed him. Lois convinces him to reverse the spell and bring Superman back.
Once Superman was back, Lois goes home and begins to pack. She feels that since Clark would never had married her if he'd still known he was Superman she wasn't going to hold him to their marriage.
Of course, Clark/Superman tells her that while she was probably right, being married to her has made him realize how much he loves her and that he still wants to be married to her. They live happily ever after. (at least until Infinite Crises, where the earth 2 Lois and Clark finally cash in their chips).
At least I think that's the story.
Tank (who always liked that particular story)
