I've read a lot of time travel fix its over the years in multiple fandoms. It's one of my fav flavors of fanfic if you will, but I came to a realization recently that FFVII has a tendency to deal with a certain element in a way I don't think I've ever seen in a different fandom...
I've only seen FFVII really grapple with the realization that going back in time means you basically erased everyone you knew. They're all effectively dead, you'll never meet some of them and that might be a good thing if you're preventing them from suffering whatever it was that happened when you met.
You have to deal with constantly being surrounded by the ghosts of people you loved who you'll never have that same relationship with. They look at you with incomprehension or disinterest, and you have to try and be happy for them for that if you want to save the world from the misery that preceded your friendship