Michelle Williams and Jason Segel Get Serious: Actor Babysits Daughter (PHOTOS)

Michelle Williams and long time friend Jason Segel have reportedly changed the tune on their platonic relationship and have possibly fallen in love.

New sources have stated that long time friends Michelle Williams and Jason Segel have slowly started transforming their relationship into a romantic one. US Weekly reported that the romance began towards the end of February.

"They dined (and giggled) at L.A.'s Chateau Marmont Feb. 27, and then shared supper at West Hollywood's Comme Ca March 16," the magazine confirmed.

Williams, who first appeared in the teen drama "Dawson's Creek," recently won a Golden Globe for her portrayal of Marilyn Monroe in the film "My Week With Marilyn." The 31 year-old actress, who has one daughter with the late actor Heath Ledger, has not dated openly since the actor's tragic death in 2008.

A source recently told US Weekly that Williams and Segel have taken their relationship up a notch.

"They are smitten and very serious," the source stated. Another eye-witness confirmed the couple's closeness.

"He put his arm around her and made her laugh as they walked," the witness told US. "[They] seemed very relaxed." Photographs were taken of the couple's March 24th stroll, revealing the two exchanging smiles.

Williams has also noted that her 6-year-old daughter, Matilda, is an important part of her life.

"I just want to go back to being a mom for a while," the actress told E! news after winning "Best Actress" in January. "Everything I do is to make Matilda's world as happy and secure as possible."

It appears that Segel could be a part of that plan. The actor was spotted spending time with William's daughter while she rode her scooter down a local block. Although the two have been friends, allowing Segel to spend time with Matilda could prove to be a big move for Williams.

"She hasn't been this happy in a long time," the source told US of Williams, suggesting that despite the fact that the two celebrities live in separate states, they are "trying to make it work."

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