The Dream Machine is a machine that gives people what they want at the cost of the environment. A village discovers it and it changes how they act towards others and material wants as well as causing them to have a disregard for home and surrounding environment.
Marge is put under a lot of stress with all of her responsibilities, which include solving the problems of the rest of the family. She gradually is negatively affected by all the stress and ultimately reaches her tipping point, causing her to put herself and Maggie in danger. Her handling of the situation suggests she has poor stress management skills.