"It's all over. It's very sad, but they always were an unlikely couple, in many ways," a source said.
Boyle, 56, cast Dawson, who is 23 years younger than him, as Elizabeth in his latest movie "Trance" in 2011, reported Ace Showbiz.
The rumors about Boyle and Dawson's relationship, however, only surfaced in August 2012.
The director had confessed in an interview that his love story with Dawson started after finishing "Trance" last year.
However, Boyle refused to comment about his relationship with the "Men in Black II" actress.