Dark Mosaic

"She'd been told she was Jessica Devlin.
They said she was the illegitimate daughter of a recently deceased millionaire. Because a horrible accident had wiped out her memory, she was recuperating at the Yorkshire estate of her father's cousin - enigmatic James Bentley.
She wondered about James's relationship with her father's wife, Laura. And she was puzzled by the reasons behind Laura's incredible malice toward her.
While Jessica desperately tried to piece together her memories, she had to struggle with her compelling attraction to James. If only she didn't feel he was keeping something important from her."