The singer/actress, 26, and Comrie, 33, "mutually decided [upon] an amicable separation," a rep for Duff confirmed Friday to People magazine. "They remain best friends and will continue to be in each other's lives. They are dedicated to loving and parenting their amazing son, and ask for privacy at this time," the rep added.
A source close to Duff told the magazine, "There was no major incident -- no big event between the two of them. They really did drift apart. They have put effort and thought into this decision for a long time. They tried couples therapy, but in the end, they realized at this time, they work better as friends. And they really are great friends."