Haha! You're right, that would make a good plot. I can see the trailer now:

Kara: You're not my husband!!
Fake hubby: Of course I am, don't be silly. Don't you remember our honeymoon in Hawaii? (*provides elaborate details only she would know*.)
Kara: No, that can't be, I have proof! (*Shows him wedding pictures and albums, where to her shock, her real hubby has been replaced by this stranger*.)

--Is she crazy, is she living in an alternate universe, or is somebody playing an elaborate hoax on poor Kara? We'll have to wait for the direct-to-video release to find out!