User blog comment:SoulRise99/HISHE: How Fairy Tail Should Have Ended/@comment-3045936-20170728223500/@comment-47.150.116.157-20170731163804

Not necessarily. Natsu's last words to Lucy leave the readers to make their own conclusions on how the duo feel about each other. Besides, Happy implied that Natsu wanted to spend his future with Lucy right before Natsu was teleported by Acno. So while NaLu may not be canon, Mashima leaves the possibility.