Google co-founder Sergey Brin has filed for divorce from his wife after learning she was having an affair with the tech billionaire Elon Musk, according The Wall Street Journal.

Musk, the world’s richest man, and Brin, the eighth richest person, were close friends until the affair, the newspaper reported. The Tesla and SpaceX CEO has regularly stayed with Brin, and Brin helped support Musk and Tesla during the 2008 financial crisis.

In recent months, the two men have had a falling out, with Brin telling his financial advisers to sell investments in Musk’s companies, according to the newspaper.

Brin filed for divorce from his wife, Nicole Shanahan, in January shortly after learning of the affair, the newspaper said. While the couple were having issues, they were still living together when Musk and Shanahan reportedly had an affair at the Art Basel festival in Miami in December 2021.

They officially broke up on December 15.

Musk reportedly apologized to Brin at a party earlier this year, even taking a knee to express his sincerity, The Wall Street Journal reported.

Musk, 51, split from Canadian singer Grimes, real name Claire Elise Boucher, in September after dating for about three years. The businessman had twins with a senior executive at another of his companies, Neuralink, weeks before he split with Grimes.

Musk is currently embroiled in a legal battle with Twitter after he walked away from an offer to buy the social media company.

Brin founded Google in 1998 with Larry Page. He served as chairman of Alphabet, Google’s parent company, until his resignation in 2019. He married Shanahan in 2018.