After dating for a year and a half, the supermodel and her bodyguard boyfriend Martin Kirsten separated a few weeks ago, PEOPLE confirms exclusively.
Klum, 40, started dating Kirsten, 41, a few months after she filed for divorce from Seal after several years of marriage.
"Martin was there for her during a challenging time in her life and it was something she will always be grateful for," says a friend close to Klum.
Kirsten and Klum are also ending their professional relationship.
"They are no longer working together," another source close to Klum confirms to PEOPLE.
"Life is about timing. He was incredibly supportive and they were there for each other, but they're moving on now," adds the source. "They still have a great friendship."
Reporting by MICHELLE TAN