The short answer is: she has problems. Serious personal problems. This is one of those movies I didn't quite appreciate when I first saw it, then came to like more and more after several viewings. It is in one sense a subtle sort of thriller, but more significantly is a story about women who lose their place in life when the role of wife/mother is taken from them. The feeling of exhilaration that comes from the pair trying to leave the wreckage brought about by their Leopold and Loeb-like sons by taking off on a "what have we got left to lose?" adventure is high spirited and nicely offset by the increasingly dark tone. There are some very pointed lines that convey the almost innate ability for women to pick up and carry on in the face of strife (of her son's waywardness Reynolds bitterly says "I tried to be a good mother. It's not my fault his father took a powder."). One of the best selling points has to be the fantastically recreated Hollywood world full of aspiring Shirley Temples and their prodding stage mothers that Reynolds thrives in while Winters seems lost. One student performing a sidesplitting and incredibly inappropriate Mae West impression has to be seen to be believed. There is care taken to present a genuine and layered relationship between the two leading ladies that even the sinister "love that dare not speak its name" implication doesn't completely undermine.
"Pass me through your fingertips/Throw me down like an old rag/I'm not standing/Don't look back/Are you human or a dog?"