One BFF “girl crush” worth one thousand failed romances for MICHELLE WILLIAMS.

Men come and go, but women who are best friends last forever!  That’s the motto of Oscar-nominated “My Week with Marilyn” star Michelle Williams, who is stuck like glue to “Cougar Town” cutie Busy Philipps!

“Michelle and Busy have a mutual girl crush on each other,” an insider told The ENQUIRER.

“They’re soul mates who do absolutely everything together.

“Lots of people whisper behind their backs, speculating that their relationship is more than just platonic. But they’re just the best of friends.”

The two co-starred in the teen drama “Dawson’s Creek,” and Busy, 32, has been married to screenwriter Marc Silverstein since 2007. They have a 3-year-old daughter.

Meanwhile, 31-year-old Michelle – mother of late actor Heath Ledger’s daughter Matilda, 6 – has dated on and off since the “Brokeback Mountain” star tragically died of an accidental overdose in 2008.

She had a post-Heath romance with indie film director Spike Jonze and she was recently spotted out with “Muppets" star Jason Segel.

“But there’s nothing serious going on,” said the source, adding: “Nothing will ever touch the feelings she had for Heath. He was the love of her life.”

Recently, Michelle sparked rumors when she took Busy as her date to this year’s Golden Globes and Oscar ceremonies.

“The truth is that Michelle is reluctant to dive back into the dating scene,” said the source. “Frankly, she’s more comfortable having Busy by her side.”