The movie begins with a dog, and ends with a dog. A dog can be fierce, but also docile at the same time, this somehow mirrors Romy, who appears to everybody to be a powerful woman but secretly desires to be tamed and given orders.
She never experienced an orgasm with her husband, and this unfulfilled sensual desire led her to have an affair with the new intern at her company, spiraling things out of control.
People start to notice what was going on between the two: her assistant took advantage of her, trying to replace her in the company; her husband distanced himself from her, and her daughter, Isabel, that she always worried about, started to worry her instead.
Romy began losing control of her life that she always maintained in the past, slipping into darkness and needed to be saved, finally saved by Isabel.
This is a lost battle of rationality against primal instinct, Ego cannot never win Es. But this is what makes us human, and not machine.