User blog comment:IamJakuhoRaikoben/Chapter 431 & 432: My sword is... & Brair in Love, Review./@comment-25334245-20150428225357/@comment-9595671-20150429121744

I agree, since Rogue's job was to go to their base it seems like what happened in the original timeline was that when they got their Gray had to prove his loyalty for some reason that Rogue may have caused by accident. To prove he was loyal, he was forced to take Frosch's life.

Or while there, one of the members may have made Gray indirectly kill him. Remember one of them had that Cursey doll, so he may have caused Frosh to move in front of one of Gray's attacks, and that attack was strong enough to kill him.

So I'm pretty convinced that future's gone, and Rogue not falling to his shadow might be a huge factor in changing the result of the fight with Acnologia.