When does Quiet leave?

[Orion 1 | Glitch]

Currently playing through for the first time, I've heard that there comes a point in the story where Quiet will leave if the player doesn't have the Butterfly emblem equipped. I'm planning to make a save backup before this happens, play through normally, then later load the backup to prevent her from leaving. However, I need to know when she leaves exactly so I know what point to create my save backup at. So, yeah. Also, no story spoilers, please.

[GetToTheTop]

I don't know where you got the butterfly emblem thing from but she leaves no matter what as part of the plot in the mission "a quiet exit". You can get her back by replaying the mission where you got quiet in the first place a few times but I don't recommend it because it doesn't make any sense why she would remain with you after the mission she leaves.

[F430]

She leaves rather late in the game. Can't make it any more specific since you don't want anything spoiled.
The butterfly emblem thing is true; it will prevent her from leaving but also won't allow certain story part leading up to her departure to happen in the first place.

[Orion 1 | Glitch]

Originally posted by F430:

She leaves rather late in the game. Can't make it any more specific since you don't want anything spoiled.
The butterfly emblem thing is true; it will prevent her from leaving but also won't allow certain story part leading up to her departure to happen in the first place.

I've heard it's somewhere in the Mission 41-43 range, but the way I heard it described was kinda weird. Could you just tell me the specific number of the mission after which it's no longer possible to prevent her leaving?

[F430]

Had to refresh my memory on this.
Mission 41, while not strictly speaking storyline-related, seems to be the starting point of it all.
A guide claims that once you finish this mission, certain things happen and after 3 or so extra missions, you will get notified that she left.

TL;DR if you want to keep her, use the butterfly emblem. You can also add "sniper" and "quiet" words to the emblem to be sure, since I heard that may or may not be a requirement too.
But if you still want to back the savegame up, do so before launching M41.

[dj8472]

If you use the butterfly emblem you won't unlock the main missions related to quiet leaving, even if she leaves you can get her back by playing the mission where you first capture her{mission 11) seven times and capture her every time, on the seventh the Mission should be named
Mission 11 [reunion] Cloaked in Silence