The `Lord of the Rings` actor - who has been dating the Gogol Bordello drummer for more than five years - broke off the relationship because he couldn-t commit to her long-term.
A friend said: "Elijah just didn`t want to settle down. The last thing he wanted to do was hurt Pamela, but she`s pretty cut up about the break-up."
The pair met on the set of 2005 adventure movie `Everything Is Illuminated`, which starred Elijah and Pamela`s band.
Elijah has been notoriously private about his relationship, but Liev Schreiber - who directed the 29-year-old star in `Everything Is Illuminated` - previously claimed he has a "sincere goodness as a human being" and a "generosity of spirit".
Despite keeping their partnership quiet, the pair were often seen together at events - she often accompanied him to movie premieres and they were both a regular of fashion week shows.
However, at the recent premieres for his new movie `The Romantics` in New York and San Francisco, Pamela was not in attendance.