Michelle Williams Was 'Not Ready' to Commit to Jason Segel: Source

02/28/2013 at 03:00 PM EST

From the outside, it seemed as though Michelle Williams couldn't get enough of boyfriend Jason Segel. In reality, the actress may not have seen him as forever material.

"She cares a great deal for Jason but is not ready to make a commitment," a source tells PEOPLE. "Maybe if they were together day-to-day, she would have more confidence in a future. But not at this time."

Dating for a year, PEOPLE confirmed on Tuesday that the pair called it quits, citing long distance as the primary reason.

"Jason never got rid of his place in L.A., and Michelle's life with [daughter] Matilda was and has always been in New York," a second source says. "While Jason made every effort to make them a priority in his life – and they were top priority – he still couldn't drop everything and leave his life and career in L.A."

PHOTOS: 5 Reasons We're Mourning Michelle & Jason's Split

The road to romance has not been an easy one for Williams, 32.

The actress's ex, Heath Ledger, was found dead of an accidental prescription drug overdose in 2008, less than a year after they split. Left to care for their daughter alone, Williams stayed out of the spotlight, but began dating director Spike Jonze for about a year. Following their split, she didn't have a public romance again until Segel, 33, in 2012.

• Reporting by JENNIFER GARCIA and LINDA MARX