She sounds depressed to me too. Often parents don't realize how much their depression affects their children because they're not doing anything to mistreat their children and are taking care of their basic needs, but having a depressed parent who is not interested in spending time with their children is damaging to kids too. If I were you I would gently point out that she sounds depressed, and how that can negatively affect her children and suggest she talk to someone because she deserves to enjoy her life and her children, and her children deserve to have a parent who is present both mentally and physically.
I haven't got the slightest idea how to change people, but I still keep a long list of prospective candidates just in case I should ever figure it out.