Complex sentence: Rachel's inexperienced but attractive new assistant at Polo Ralph Lauren, whom she hires after being promoted, not because he is the best choice for the job but because she is smitten with him, bemusing him with her daft behavior around him.
Split into simpler sentences: Rachel's inexperienced but attractive new assistant at Polo Ralph Lauren. She hires him after being promoted, not because he is the best choice for the job but because she is smitten with him, bemusing him with her daft behavior around him.