Complex sentence: She shared much of her life with Gerstner (whom at this stage she was not able to marry), together visiting Parisian Haute couture fashion shows, and visiting the high-profile fashion designer Jacques Fath out of town.
Split into simpler sentences: She shared much of her life with Gerstner, whom at this stage she was not able to marry. Together they attended Parisian Haute couture fashion shows, and visited the high-profile fashion designer Jacques Fath out of town.