The relationship history of Elon Musk, who says he must be in love to be happy

• Tesla and SpaceX CEO Elon Musk was interviewed for an intensely candid Rolling Stone profile.

• He discussed his views on relationships and loneliness.

• Musk has been married twice, and recently split from his girlfriend actress Amber Heard.

Elon Musk got candid about his personal life in an in-depth Rolling Stone interview.

He spoke of his breakup with ex-girlfriend Amber Heard, expressing his heartbreak over their parting.

It's an unusual move for Musk, who said in 2010 that he would "rather stick a fork in my hand than write about my personal life."

The CEO of Tesla and SpaceX went on to discuss how difficult it is for him to meet people, saying he is looking for a long-term relationship — and a soul mate. Musk even asked interviewer Neil Strauss if there was anyone Strauss thought he should date.

"If I'm not in love, if I'm not with a long-term companion, I cannot be happy," he told Rolling Stone. "I will never be happy without having someone. Going to sleep alone kills me. It's not like I don't know what that feels like: Being in a big empty house, and the footsteps echoing through the hallway, no one there – and no one on the pillow next to you. F--. How do you make yourself happy in a situation like that?"

Here's a look at some of the tech titan's past relationships:

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DON'T MISS: A look at the demanding schedule of Elon Musk, who works in 5-minute slots, skips breakfast, and largely avoids emails

Musk told Rolling Stone he's struggled with loneliness since childhood. "When I was a child, there's one thing I said," Musk said. "'I never want to be alone.'"

Source: Rolling Stone, Business Insider

Musk met his first wife, Justine Wilson, at Queen's University in Ontario. Writing in Marie Claire, Justine — who uses Musk's last name — recalled Musk invited her out for ice cream.

Source: Marie Claire

She decided to stay in to study, but he showed up with "two chocolate-chip ice cream cones dripping down his hands." Musk transferred to Wharton, but kept sending Justine roses. They went their separate ways, but reconnected as Musk started working on his first startup and Justine started working on her first novel after graduation.

Source: Marie Claire