Bad habits are hard to fix after a single attempt, and in Volume 3, she saw Adam effortlessly dismember the arguably strongest member of her team. If he can take down Yang in a single move, what chance do the others have against him? Of course she was afraid for their safety.
The culmination didn't come out of nowhere. It came out of Sun getting injured, Blake telling him "That's why, damn it! You just proved me right!", and Sun telling her "Wow, you're being an idiot, here's what I mean by that." And now, instead of running or hiding, Blake has decided to stand and fight and take back the White Fang. Even with Ilia begging her to leave Menagerie "before it's too late", Blake outright refuses to leave, telling her "You're going to have to make me." That line right there seems like "I'm not gonna run anymore".