According to People, the separation between Klum, 40, and her boyfriend Kristen, 41, happened a few weeks ago.
“Martin was there for her during a challenging time in her life and it was something she will always be grateful for,” a source told People.
Kirsten and Klum have also ended their professional relationship.
“They are no longer working together,” another source told the mag.
They began their relationship 2012, a few months after she filed for divorce from husband Seal, ending a marriage that lasted seven years.