Klára married Ferenc Engel in Budapest. Very little information exists about Ferenc Engel or the specifics of their relationship. The reasons for their marriage and eventual divorce are not publicly documented.

Klára married György Eszterházy. Again, details about their relationship are scarce. This marriage also ended in divorce, though the exact timing is unclear.

Met John von Neumann while he was visiting Budapest. At the time, von Neumann was already a renowned mathematician at Princeton University. Their shared Hungarian background and intellectual compatibility likely played a role in their connection.

Klára married John von Neumann shortly after meeting him in Budapest. This marriage would significantly alter the course of her life, moving her to the United States and introducing her to the world of computing.

John von Neumann died from bone cancer. This was a profound loss for Klára, ending their nearly two-decade-long marriage and leaving her to navigate life without her intellectual partner and husband.

Klára married Carl Eckart, a prominent physicist and oceanographer. This marriage indicates a continued desire for companionship and intellectual connection after the loss of von Neumann. They remained married until her death.