New York, Jan 26 (ANI): Natalie Portman is keeping mum over her relationship with choreographer Benjamin Millepied because she doesn't want to be projected as a home wrecker.

Millepied, 32- the New York City Ballet dancer-is choreographing the 'Closer' star in her new movie, 'The Black Swan'.

And reports suggest that Natalie was the reason behind Millepied's break up with his girlfriend of three years.

"They've been dating since the fall, although she told friends that she hasn't gone public with it because she was waiting to see if things got serious," the New York Post quoted a source as saying.

"But the real reason she was quiet about things is that Ben had a live-in girlfriend of three years when they met. She was a ballerina at the American Ballet Theater. She had been talking about marrying him and was blindsided by the split. She moved out right after New Year's Eve," added the source.

A spokeswoman for Portman said: "We have no comment about her personal life." (ANI)