User blog comment:4 Number the Ness mainer/Thoughts on Chapter 424: Avatar/@comment-25693405-20150311184441

Generally I consider it useless to speculate, since we'll find out in a week anyway, but this time I'll make an exception.

Gray mentioned that he was going to go after Acnologia and Zeref, so he's probably on a journey and Juvia's just depressed because he's not around. Given whom Gray is after, its entirely possible that he got himself killed (but this isn't likely given the nature of the show)

Personally, a few things Gray's done have set off my gaydar... But that's just my personal theory of why he keeps rejecting Juvia.

It's also possible that Mashima's trolling us and these are Juvia's tears of joy...but probably not