Kristen Stewart has reportedly pulled out of her first scheduled public appearance since news broke that she had an affair with director Rupert Sanders.

The 22-year-old actress is said to be distraught over the breakup of her relationship with her Twilight co-star Robert Pattinson.

And RadarOnline claims that the brunette beauty is not ready to face the limelight as she comes to terms with the ramifications of her actions.

"Kristen won't be doing the red carpet for On The Road she's too ashamed to show her face in public right now," a source told the site about the August 16 event.

"There's also the dilemma of standing next to her co-star in the movie, Tom Sturridge. He's very close to Rob and Kristen thinks it would be awkward for her to promote the movie on the red carpet alongside him.

"Kristen is very proud of her work for On The Road, she grew up reading Kerouac novels and this is a production she always wanted to star in.

"If she appears at the London premiere, it will detract people from the movie itself and Kristen doesn't want that at all."

Meanwhile, Rob is set to make his first appearance on The Daily Show with Jon Stewart next Monday.