'Oppenheimer' depicts the scientist's affair with Jean Tatlock. Here's the real story about Oppenheimer's relationships with Tatlock and Ruth Tolman.

The movie explains that Oppenheimer met psychiatrist Jean Tatlock while he was teaching at the University of California, Berkeley, in the 1930s.

The pair's romantic relationship escalated as Tatlock got Oppenheimer interested in politics, largely because she was part of the Communist Party USA.

Oppenheimer explicitly explained his relationship with Tatlock when speaking at his federal security hearing in 1954 – which is also seen in the film. 

He said: "In the spring of 1936, I had been introduced by friends to Jean Tatlock, the daughter of a noted professor of English at the university; and in the autumn, I began to court her, and we grew close to each other. We were at least twice close enough to marriage to think of ourselves as engaged. Between 1939 and her death in 1944 I saw her very rarely." 

In the transcript (which is still available to read in its entirety), Oppenheimer confirmed that he visited Tatlock in 1943 at her San Francisco apartment, only a few months before her death.

"Our meetings were rare. I do not think it would be right to say our acquaintance was casual. We had been very much involved with one another and there was still very deep feeling when we saw each other. … I visited her, as I think I said earlier, in June or July of 1943," he said.

Tatlock died by suicide on January 4, 1944, though there is some debate about whether she was murdered by Manhattan Project intelligence agents.

Although Oppenheimer had an on-and-off relationship with Tatlock, he married Kitty in 1940, shortly after she fell pregnant. That in itself was a scandal since Kitty was married to Richard Harrison at the time, but she divorced him during the pregnancy.

When directly questioned, Oppenheimer confirmed that he "spent the night" with Tatlock in 1943. So it seems highly likely that Oppenheimer did cheat on his wife with Tatlock.

Tatlock wasn't the only woman that Oppenheimer had a connection with outside of his marriage to Kitty, as he allegedly had an affair with Ruth Sherman Tolman, a psychologist who worked for the Office of Strategic Services.

Tolman was 10 years older than Oppenheimer, and was also married to Richard Tolman — a physicist in Pasadena who advised the Manhattan Project. 

Nolan's movie uses this in the story, suggesting that Oppenheimer started having an affair with Ruth (Louise Lombard) to spite Richard (Tom Jenkins) because he was originally left out of a meeting about the Manhattan Project. 

Nolan's film is based on Kai Bird and Martin Sherwin's 2005 book about Oppenheimer, called "American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer." Bird and Sherwin suggest that Tolman and Oppenheimer had a "very caring and sweet affair."

This is backed up by the 2013 book, "An Atomic Love Story: The Extraordinary Women in Robert Oppenheimer's Life," by Shirley Streshinsky and Patricia Klaus, which says the affair "was not believed to have been sexual, only a close emotional bond and connection."

Oppenheimer stayed with Kitty and raised a family with her until his death in 1967. They had two children, Peter and Toni.