User blog comment:LegerPrime/Natsu vs. Acnologia/@comment-1153699-20151012205449/@comment-7418318-20151013063932

"Would Natsu have returned if he wasn't near Acnologia?"

Due to the timing with Frosch's supposed death and the GMG I would certainly think he would have came back around this date no matter if his training is finished or not.

Besides, how could Natsu really measure if he's strong enough to defeat Acnologia?