Lois's body is switched with her counterpart in the future. She is trapped there for some time. When it is time for her to return to her own time (without her memories of the switch), the last line of the story is something to this effect (from Clark) "I can't wait to fall in love with you again."

Here are the ones that come to mind:

Riochet by Sue S.

Switch or Not Again by kipp.

Thank you for the suggestions. I've read Ricochet. On my way to reading Switch and "Not Again."

Any other ideas out there?

Hmm. Disruptions in Time (ML Thompson)? Home: Circle of Fate by Nan Smith? or Missing Lois by VirginiaR.?
That are the ones that come to my mind.

Oh, and "oops: Destruction of Utopia" by ML Thompson alsohas a similar premise

I just discovered "Foreshadowing" by HappyGirl today, this also fits to your description.