It looks like Josh Hartnett has decided to finally open up about his famous ex-girlfriends but unfortunately the hot actor refused to name the starlets he was referring to in particular.

According to E! News, in a new interview with Elle, the 35-year-old suggested that actors should do the opposite of his past actions and avoid dating their costars. Could he be talking about Scarlett Johansson?

Hartnett told the publication, "I don't recommend it to young actors," adding, "You can make a lot of enemies in the business that way.

"But when you work with somebody every day, it's like trial dating. You develop a fantasy about them. It doesn't always work out, does it?"

The actor admitted that although he has dated some of the most beautiful actresses and had a rumored fling with Rihanna, he has never bragged to his friends about his hot Hollywood romances. Josh Hartnett explained, "They want to hear all about what you're doing."

He went on to say, "But they don't want to hear any complaints. Back when I dated a few very beautiful, very famous girls, I said something once-it wasn't really a complaint-and my buddy said, 'Oh my God, my diamond shoes are too tight.' He coined the phrase."

The movie star also gave a tip on just how to keep a girlfriend happy when you are in the entertainment industry.

He revealed, "Let them be on set whenever they want, with whichever costar you're working with. Never say the scene is too sensitive. They get very suspicious."

It seems like Josh Hartnett has certainly learned a lot from his Hollywood girlfriends.