I think it's just a temporary switch not permanent, Ruth will have some stuff to do.
here is the relevant part... maybe it's time for the fight with whatshername? The other strengthy lady.
"In terms of a Chapter 8 update, I guess I’ll tell you a tiny bit of what to expect next time round without spoiling too much. Firstly, for the girls involved, this might be the chapter that includes the most amount of Lis and side girls overall since Chapter 3 (and that was only because you’ve got the entire Sisterhood in that one scene).
Lady Steel will be taking a break from being your bodyguard, but don’t worry, she still plays a significant part in the chapter. She does have an important event happening after all. Instead, you’ll be looked after by Emerald for the day, so a lot of your time in the chapter will be spent with these two Sisters, along with Evelyn & Lucia (if you’re on her path). Cat and Marina also need some explanations. And then you’ll get appearances from five other girls too.
Also, while there will be some bonuses for being on the “manipulate Lucia” path, there’ll be significant payoff if you’re on the Normal path too. So those of you who are nice are going to get a whole heap of character growth (I hope).
I’ll warn you though, whichever path you have chosen, you’re going to need an Emerald save for some other fun stuff.
Ideal playthrough's stats are going to be:
Evelyn + Emerald + Amber + Lucia Manipulate
Evelyn + Emerald + Lucia Normal"