Hard Truth About Albert Einstein

Einstein was a ladies' man:

Einstein's Wives and Affairs....:-o

First wife, Mileva

Mileva Maric was the only female physics major at the Polytechnic in Zurich, where Einstein went to college. During their second semester, Einstein and Mileva began to take interest in each other. Their relationship developed into a romance that eventually led to marriage, in spite of strong opposition from Einstein's family (especially his mother).

Second Wife, Elsa

After Einstein divorced Mileva (his infidelity was listed as one of the reasons for the split), he soon married his cousin Elsa Lowenthal. Actually, Einstein also considered marrying Elsa's daughter (from her first marriage) Ilse, but she demurred:

Before marrying Elsa, he had considered marrying her daughter, Ilse, instead. According to Overbye, “She (Ilse, who was 18 years younger than Einstein) was not attracted to Albert, she loved him as a father, and she had the good sense not to get involved. But it was Albert’s Woody Allen moment.”

Einstein's Affairs

Unlike Mileva, Elsa Einstein's main concern was to take care of her famous husband. She undoubtedly knew about, and yet tolerated, Einstein's infidelity and love affairs which were later revealed in his letters:

Previously released letters suggested his marriage in 1903 to his first wife Mileva Maric, mother of his two sons, was miserable. They divorced in 1919, and he soon married his cousin, Elsa. He cheated on her with his secretary, Betty Neumann.
In the new volume of letters released on Monday by Hebrew University in Jerusalem, Einstein described about six women with whom he spent time and from whom he received gifts while being married to Elsa.
Some of the women identified by Einstein include Estella, Ethel, Toni and his "Russian spy lover," Margarita. Others are referred to only by initials, like M. and L.
"It is true that M. followed me (to England) and her chasing after me is getting out of control," he wrote in a letter to Margot in 1931. "Out of all the dames, I am in fact attached only to Mrs. L., who is absolutely harmless and decent." 

(source)