"There is turmoil in the relationship," a source tells PEOPLE
“There is no rush to marry at the moment,” says a longtime friend of Depp. “Johnny is crazy in love with Amber, but there is turmoil in the relationship.”
At 28, Heard has established herself as a free spirit who is on the record about everything from her skill with a .357 Magnum to her bisexuality. She is also 23 years younger than Depp, a factor in their relationship challenges.
“Amber flirts and has many different kinds of relationships,” the source says. “She is not really ready to settle down.”
For his part, Depp recently raised eyebrows with a rambling appearance at the Hollywood Film Awards in November. And he told Details that his busy career has him racing at a “schizophrenic” pace: “It’s been insane.”
For more on Depp and Heard’s relationship, pick up this week’s issue of PEOPLE, on newsstands Friday
• Reporting by LINDA MARX