User blog comment:Miskos3/Fairy Tail 530: Neo Eclipse, Review/@comment-29874610-20170408214444/@comment-7418318-20170409132232

With the way Gray already came close to going insane (or did go insane depending on your opinion) for a while in the prime timeline I think we got a pretty good idea of how it might have happened. Considering the stuff that would have to happen to bring F-Rogue back into the story just to get an explanation that is ultimately nothing more than a minor curiosity... I would prefer F-Rogue to stay out of the remaining story.

This particular little fact is better answered in interviews, volume afterwords or Q&A than in the story itself if you ask me.