Final answer:
In 1814, Percy Shelley eloped with Mary Wollstonecraft Goodwin, who is later known as Mary Shelley. This began a period of professional collaboration and personal strife, set against a backdrop of radical thought and exile.
Step-by-step explanation:
In 1814 Shelley left his wife and moved to the continent with Mary Wollstonecraft Goodwin, who would later become known as Mary Shelley. Their mutual attraction was described as electric, and they eloped to Switzerland. This move was highly controversial as Shelley was still married to his first wife, Harriet Westbrook, at the time. This step in Shelley's personal life prefaces a period of intense creativity and emotional turmoil, marked by his radical poetry and eventual self-imposed exile from England.
While in Italy, Shelley associated with other expatriates and his writing continued to evolve, influenced by personal tragedies such as the death of his daughter Clara, as well as the harsh political realities of the time including the growing pains of the Industrial Revolution and the expanding British Empire. Mary Shelley, who was also an accomplished writer, penned the classic novel Frankenstein during their time in Italy.