In Edge of Tomorrow, when Cage asks Rita if she's tried having sex to get the time loop ability back, with whom does she mean, since they are the only 2 who have had the ability?
I don't think we should interpret Rita's response to mean she tried using sex to get the ability back after she had lost it.
Instead, I think Rita tried to transfer the ability from herself to the person she was in love with during her cycle at Verdun. (i.e. while she still had the ability.)
She watched that person die ~300 times, and tried everything she could think of to save them and/or share her "gift" with them. Hence her strong conviction that Cage would not be able to give it back to her again (through any means).
I think it's a mistake, made in the script and shouldn't be there because it's a ridiculous notion, if she still had it she wouldn't have tried having sex with anyone in the hope of getting it back, unless it was one of the aliens - or she might have tried passing it on, but in that case she hadn't lost it. right? so it's either her old boyfriend or an alien, don't think the alien would be so receptive though.