Some of them write their fanfics with a post-Hogwarts setting and they make it so that Lily survives and James doesn't.
Before you ask, "wtf Salma how is this good", let me explain.
By doing this, they aren't making so that Lily cheats on or leaves James for Snape.
By doing this, they aren't disrespecting Lily as a character by turning her into a cheater with shallow morals.
So if you ship Snily and this is how you write your fanfics, congrats! You are the only Snily shippers that have my respect as I absolutely hate the ship.