The 50-year-old SpaceX founder has confirmed that he and the Canadian singer, 33, have broken up.
"It's mostly that my work at SpaceX and Tesla requires me to be primarily in Texas or traveling overseas and her work is primarily in LA," he added. "She's staying with me now and Baby X is in the adjacent room."
The news was announced one week after SpaceX's Inspiration4, which featured an all-civilian crew, splashed down safely off the Florida coast.
Reps for Musk and Grimes did not immediately respond to PEOPLE's request for comment.
Taylor Hill/Getty Images Grimes (L) and Elon Musk
Musk and the musician were first romantically linked in May 2018, when they made their public debut at the Met Gala following his split from Amber Heard.
Elon Musk Twitter Elon Musk and son X
"I do actually just really love my boyfriend," she said at the time, adding of their relationship, "No one believes me about this, but I just did not understand what I was getting into at all."
"Not that I'm mad about it. I just didn't think it would be a thing," she continued. "The s— that's happened with my boyfriend this year has overwritten so much of my life's work."
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Since welcoming their son last May, the Tesla founder has been open about how Grimes has been taking a more active parenting role in their baby's life.
"Well, babies are just eating and pooping machines, you know? Right now there's not much I can do," he told The New York Times in a July interview.
"Grimes has a much bigger role than me right now," he continued, adding, "When the kid gets older, there will be more of a role for me."
Musk, who was married three times — twice to Talulah Riley — has five sons from a previous marriage. His first son, Nevada, died tragically of SIDS at 10 weeks old in 2002.