No, the affair between Albert Einstein and Marilyn Monroe depicted in the TV show "The Big Bang Theory" is fictional. There is no historical evidence or credible documentation to support the claim that Einstein had an affair with Monroe or any other romantic involvement with her. The storyline in the TV show is purely fictional and not based on any real events or facts. It's important to remember that "The Big Bang Theory" is a work of fiction and often incorporates comedic and exaggerated elements for entertainment purposes.