Patton – who married Thicke in 2005 – cited "irreconcilable differences" in papers filed in Los Angeles on Oct. 3 and is asking for joint custody of their son, Julian Fuego, 4.
"We will always love each other and be best friends, however, we have mutually decided to separate at this time," the couple told PEOPLE in a statement this past February when they announced their split.
The months that followed would bring multiple public apologies from Thicke, who has faced rumors of infidelity as well as his admitted drug and alcohol abuse.
"I told my wife the truth. That's why she left me," the singer said in April during a deposition for an unrelated legal matter.
"We've known each other since we were teenagers," Patton told Vanity Fair in May of her husband, who was 14 when they met. "All I can tell you is there's a deep love there – always was, and always will be."
A source close to the couple tells PEOPLE, "All is peaceful between Robin and Paula."