Amber Heard and Elon Musk Split After a Year of Dating

Amber Heard and Elon Musk have called it quits.

The stars' whirlwind, date-filled romance has come to an end a little more than a year after they were first linked last summer, a source tells PEOPLE.

"They are no longer dating," says the source.

According to the source, Heard and Musk's increasingly busy schedules contributed to the split.

"They had fun for a few months, but are both very busy with work now. It was getting hard to find time to see each other," says the source, adding that Musk initiated the split. "Elon's is working day and night. This is his life and he loves it. He is in no position to be in a relationship right now and ended it."

Dating rumors began swirling last year when the actress and Musk were spotted out together several times amid their respective divorces — Heard's contentious divorce from actor Johnny Depp was finalized in January and Musk filed for divorce from wife and Westworld actress Talulah Riley in January 2015.

The breakup comes as a shock, as the former love birds were recently spotted out, both donning smiles, in Los Angeles in June. One month earlier, Heard and Musk spent some time Down Under while Heard filmed Aquaman.

In May, a source told PEOPLE that the stars were "very serious about each other."

"She spends a lot of time at his house and is very comfortable there," the insider said. "Amber's also gotten to know his kids and spends time with them as well."

Although they began spending time together after Heard's divorce, the Tesla founder first took interest in Heard in 2013 when he appeared in Robert Rodriguez's film Machete Kills.

"When the time was right and they were both single last year, he started pursuing her romantically," a source previously told PEOPLE. "She was playing hard to get for a while, which made him even more interested."

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Heard made the couple's romance Instagram official in April with a photo of herself resting her arm against Musk, a kiss-mark clearly visible on his cheek.

The actress and Musk were first seen together in Miami, where they were both staying at the Delano South Beach in July 2016.

"Elon is attracted to her edginess. She isn't frightened about being different," a source told PEOPLE of Musk. "She doesn't get easily intimidated. She is very focused and loves to learn."

Musk has five sons from a previous marriage.