Later Lois finds that she has super-powers of her own, guessing that she gained them from the Man of Steel. She puts on a super-costume that she has from a previous adventure.
When the un-Super-man presses her on the question of marriage, Super-Lois says nix to the idea, because he would be in too much danger.
In the end it turns out this was a Superman robot and not the real Man of Tomorrow. The robot took the place of the Metropolis Marvel and arranged the experiment at the Fortress to test Lois Lane's loyalty to his master.
Note: Lois wears the same costume she wore in SUPERMAN'S GIRL FRIEND, LOIS LANE 17 (May 1960)--2nd story, "Lana Lang, Superwoman" by Siegel, Swan and Kaye--in which the Man of Steel offers Lana Lang a transfusion of his blood. She accepts and becomes a Superwoman. He then does the same for Lois, who also gains super-powers and dresses in this green super-outfit. Kal-El did this to protect them from an attack by Brainiac.
"The Reversed Super-Powers" was written by Jerry Siegel, but even if that was known when this story was reprinted, Jerry would never have got any credit. While it's true sometimes that it was hard to find out the writers and artists for these stories--Siegel and Shuster were a special case as it was company policy to erase any credit. The exception being SUPERMAN FROM THE 30S TO THE 70S, which comes out in 1971--that did keep Jerry and Joe's names on the stories; while this was edited by E.Nelson Bridwell, it was published by Bonanza Books, which wouldn't have been involved in the legal dispute with the creators.