Witherspoon, who also worked with Vallée on Wild, for which she was nominated for an Oscar for Best Actress, in 2015, was devastated.
"My heart is broken," she wrote on her Instagram Story, alongside a photo of the two together. "My friend. I love you."
Meanwhile, Woodley used one image, which appears to be him preparing a meal, under several captions, to express her hurt, in a stream of consciousness posting.
"I am in shock," she began. "Complete and utter shock. My f****** god death is the worst."
"But I guess somehow I know you will turn it into a grand adventure ... one for the books," she added. "One I cant [sic] wait to read & to watch when my time comes."
Then, "It doesn't make sense though dude. It doesn't make sense. ... Maybe when we wake up tomorrow you'll be there laughing saying it was just a satirical short film you made. That it's not real."
She asked, "Did you ever want it? Did you want it bad?"
"Oh my, it tears me apart," she concluded.
The women were part of an ensemble cast, which also included Laura Dern, Nicole Kidman, Zoë Kravitz, Adam Scott, Alexander Skarsgård and, in its second season, Meryl Streep. Based on a 2014 book by Liane Moriarty, the HBO drama centered on the lives of upper-class mothers at a prestigious elementary school by the sea. It won a total of eight Emmys, including nods for Witherspoon and Woodley. In 2017, Vallée himself won an Emmy for directing the project.
Dern sent the director a love letter in the following hours. "The world has lost one of our greatest and purest artists and dreamers," she captioned a photo of the two laughing together. "And we lost our beloved friend. Our hearts are broken."
Beautiful Jean-Marc Vallee. The world has lost one of our great and purest artists and dreamers. And we lost our beloved friend. Our hearts are broken. pic.twitter.com/v9WXikI48e
— Laura Dern (@LauraDern) December 27, 2021
Matthew McConaughey and Jared Leto, who starred in Vallée's Dallas Buyers Club, the 2013 drama that earned each of them an Oscar, followed suit.
In a poetic message, McConaughey said that "love stories were everywhere in [Vallée's] eye."
Meanwhile, Leto called Vallée "a filmmaking force and a true artist who changed my life."
A filmmaking force and a true artist who changed my life with a beautiful movie called Dallas Buyers Club. Much love to everyone who knew him. Life is precious. pic.twitter.com/2DT0tu9Lbo
— JARED LETO (@JaredLeto) December 27, 2021
"Life is precious," he concluded.