There are many rumours about the two of them getting together. Sometimes it's them meeting and Marilyn saying something like "Think of the children - my looks, your brains". She is reported to have mused about what it would be like to be with Einstein (who was into "free love"). When she died they reportedly found an autographed photo of Einstein's in her effects.
Who knows? I can't see Einstein saying no to her.
Put this just a little on topic, there's a diary entry by Marilyn where she speculates about Clark Gable spanking her.
http://www.contactmusic.com/new/xmlfeed.nsf/story/monroe-fantasised-about-being-spank ed-by-daddy-gable has the details.
Goodgulf