Helen Hunt and Matthew Carnahan split after 16 years together

After 16 years together, Helen Hunt and Matthew Carnahan have called it quits.

"They had a rocky relationship and many offs and ons over the years," a source told E! News. "They stayed together as long as they did because of their daughter. They've split up before, but this time seems to be different."

The actress, 53, and her writer-producer ex, 56, share a daughter, 13-year-old Makena.

Although neither party has spoken publicly about the split, rumors are already swirling. One source told In Touch that it was a "very messy" breakup.

Hunt has retreated from the spotlight in recent years after working nonstop in the '90s and early 2000s, but two years ago, she told press that she and Carnahan were teaming up to develop a series. "It's a very exciting time. I'm developing a show with my partner, Matthew Carnahan, who runs House of Lies," she told The Daily Beast. "It's something he's written that we'd make together and I'd be in."

It's unknown whether that project ever moved further into development.