Cressida Bonas split with Prince Harry after intense scrutiny of their relationship on social media and in public, according to a royal biographer.
Ingrid Seward, a writer who is also friends with Miss Bonas' mother, revealed the actress, 27, told friends she became fed up with the "awful" situation as she was continuously criticised, both in the street and online.
Miss Bonas, who is also a model, split with the Prince in 2014 amid speculation she could not cope with his highly public lifestyle.
Speaking at the Henley Literary Festival, Mrs Seward confirmed Miss Bonas told friends she split from the Prince after two years having been faced with a barrage of negative comments whenever they went out.
"She just said it was awful because every time she walked down the street she could hear people criticising her," Mrs Seward said. "They would whip out their phones and take photos of her. They'd say 'oh look at her hair', 'oh look at her clothes, look at her boots, she hasn't got her laces done up', I mean this is just a normal, pretty girl and she just couldn't take it. She just thought 'why are they getting at me?'."