A spokeswoman for Patrick confirmed to The Associated Press on Monday that the drivers are "no longer in a relationship."
Patrick didn't attend the season-ending awards ceremony last month in Las Vegas with Stenhouse, who was honored for making NASCAR's playoffs in 2017. That led to speculation about the most high-profile couple in motorsports.
Patrick and Stenhouse announced they were dating in early 2013. She confirmed that by telling the AP: "I have a boyfriend, his name is Richard."
It was an unconventional pairing. They raced against each other weekly, and over the course of their relationship they clashed competitively, leading to post-race disagreements.