Much of their time together was spent in Kahlo's famous home, La Casa Azul in Mexico, where photographer Nikolas Muray also shot home videos of the eccentric couple.
A Frida Kahlo fan page on Facebook posted some of Muray's footage in a rare video, which shows the two iconic artists kissing and embracing each other.
In the video, a narrator recites an excerpt that Kahlo wrote about her love for Rivera in her diary.
"Nobody will ever know how much I love Diego,” says the narrator reading Kahlo’s words. "I don’t want anything to hurt him, nothing to bother him and rob him of the energy he needs for living -- for living as he likes, for painting, seeing, loving, eating, sleeping, being by himself, being with someone. But I’d never want him to be sad. If I had good health, I’d give him all of it. If I had youth, he could take it all."
Watch the rare video of Kahlo and Rivera above.