Your girlfriend has advanced in her job and become general manager. It sounds as if she has got more responsibility and has to handle many new problems every day. This is not easy for her to manage, and she has to attend much more to the problems of her work.
What she needs from you is that you understand how pressed her new life is, and that you take over more of her previous responsibility in managing your home and children. When she has grown accustomed to her new work, she will not be so pressed, and will hopefully become more of your old girlfriend.
It is not easy for a woman to both work full time and then come home to a messy home with many children with different demands. If you have food ready when she comes home, longing for rest and relaxation, and give her the security that the home works when she is at work, then you give her the chance to feel her love for you.
She probably feels that there are more requirements than she can cope with. She needs to feel that you give her the support a grown up man can give to another person.