User blog comment:Relikz/Chapter 384: Attack of the Celestials Review/@comment-86.70.179.150-20140516080659/@comment-7418318-20140516092812

That she lost everything else is all the more reason to remain within Fairy Tail. The guild is the only thing she has left.

If she still had some kind of old life to return to or some other people who she can live with, I can see her temporarily leaving Fairy Tail because the guild reminds her of the sacrifice she made on their behalf, but Lucy's past life is gone and she has no other people outside the guild.