Its bloody exhausting being a primary single parent, and there's no saying she didn't ask Ste to have them for a few days. He maybe just refused, or maybe she doesn't want to be away from the kids for extended periods. Which is normal. It's mentally draining and it's quite normal/common to fall into a trap of the kids being away and you want to go out and do stuff but you also want to sit at home alone in peace and not be anything to anybody for a little bit. Countless nights I spend ages getting my daughter to sleep and all I can think about it climbing into bed and putting my head down but then I end up sat on the sofa alone in the quiet looking through old photos of her/us because I bloody miss her, and she's only in the next room.
Some scenes with Amber I do find extremely shocking and I think there's definitely things she could do to help herself but it's also really hard getting yourself mentally into that place and having the physical energy to do the thing. I really feel for her. I've been there, albeit with only 1 child, and it's a really dark and difficult place to be.